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* s390/topology: use for_each_set_bit to simplify the codeWei Yongjun2012-09-261-4/+1
| | | | | | | | | | | Use for_each_set_bit() to simplify the code. spatch with a semantic match is used to found this. (http://coccinelle.lip6.fr/) Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* s390/smp,topology: add polarization member to pcpu structHeiko Carstens2012-09-261-7/+4
| | | | | | | | The cpu polarization member is the only per cpu state that is not part of the pcpu structure. So add it there and have everything in one place. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* s390/sysinfo,topology: fix cpu topology maximum nesting detectionHeiko Carstens2012-09-261-6/+4
| | | | | | | | | | | | | | | The maximum nesting of the cpu topology is evaluated when /proc/sysinfo is the first time read. This happens without a lock and a concurrent reader on a different cpu can see and use an invalid intermediate value. Besides the fact that this race is quite unlikely the worst thing that could happen is that /proc/sysinfo would contain bogus information about the machine's cpu topology. Nevertheless this should be fixed. So move the detection code to the early machine detection code and since now the value is early available use it in the topology code as well. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* s390/topology: remove sysinfo header include, add forward declaration insteadHeiko Carstens2012-09-261-0/+1
| | | | | | | | | Any change to sysinfo.h causes a whole kernel recompile since sysinfo.h is included by topology.h, which again is used nearly everywhere. So remove that include and add a forward declaration instead. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* s390/comments: unify copyright messages and remove file namesHeiko Carstens2012-07-201-1/+1
| | | | | | | | | | | | | | Remove the file name from the comment at top of many files. In most cases the file name was wrong anyway, so it's rather pointless. Also unify the IBM copyright statement. We did have a lot of sightly different statements and wanted to change them one after another whenever a file gets touched. However that never happened. Instead people start to take the old/"wrong" statements to use as a template for new files. So unify all of them in one go. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
* [S390] rework smp codeMartin Schwidefsky2012-03-111-4/+4
| | | | | | | | | | | | | | | | | | | | | Define struct pcpu and merge some of the NR_CPUS arrays into it, including __cpu_logical_map, current_set and smp_cpu_state. Split smp related functions to those operating on physical cpus and the functions operating on a logical cpu number. Make the functions for physical cpus use a pointer to a struct pcpu. This hides the knowledge about cpu addresses in smp.c, entry[64].S and swsusp_asm64.S, thus remove the sigp.h header. The PSW restart mechanism is used to start secondary cpus, calling a function on an online cpu, calling a function on the ipl cpu, and for the nmi signal. Replace the different assembler functions with a single function restart_int_handler. The new entry point calls a function whose pointer is stored in the lowcore of the target cpu and it can wait for the source cpu to stop. This covers all existing use cases. Overall the code is now simpler and there are ~380 lines less code. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* Merge branch 'for-linus' of ↵Linus Torvalds2012-01-091-88/+187
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (31 commits) [S390] disassembler: mark exception causing instructions [S390] Enable exception traces by default [S390] return address of compat signals [S390] sysctl: get rid of dead declaration [S390] dasd: fix fixpoint divide exception in define_extent [S390] dasd: add sanity check to detect path connection error [S390] qdio: fix kernel panic for zfcp 31-bit [S390] Add s390x description to Documentation/kdump/kdump.txt [S390] Add VMCOREINFO_SYMBOL(high_memory) to vmcoreinfo [S390] dasd: fix expiration handling for recovery requests [S390] outstanding interrupts vs. smp_send_stop [S390] ipc: call generic sys_ipc demultiplexer [S390] zcrypt: Fix error return codes. [S390] zcrypt: Rework length parameter checking. [S390] cleanup trap handling [S390] Remove Kerntypes leftovers [S390] topology: increase poll frequency if change is anticipated [S390] entry[64].S improvements [S390] make arch/s390 subdirectories depend on config option [S390] kvm: move cmf host id constant out of lowcore ... Fix up conflicts in arch/s390/kernel/{smp.c,topology.c} due to the sysdev removal clashing with "topology: get rid of ifdefs" which moved some of that code around.
| * [S390] topology: increase poll frequency if change is anticipatedHeiko Carstens2011-12-271-8/+26
| | | | | | | | | | | | | | | | | | | | | | Increase cpu topology change poll frequency if a change is anticipated. Otherwise a user might be a bit confused to have to wait up to a minute in order to see a change this should be visible immediatly. However there is no guarantee that the change will happen during the time frame the poll frequency is increased. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| * [S390] topology: cleanup z10 topology handlingHeiko Carstens2011-12-271-29/+48
| | | | | | | | | | | | | | | | Cleanup z10 topology handling. This adds some more code but hopefully the result is more readable and easier to maintain. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| * [S390] topology: get rid of ifdefsHeiko Carstens2011-12-271-55/+117
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Remove all ifdefs from topology code and also only compile it for the CONFIG_SCHED_BOOK case. The new code selects SCHED_MC if SCHED_BOOK is selected. SCHED_MC without SCHED_BOOK is not possible anymore. Furthermore various sysfs attributes are not available anymore for the !SCHED_BOOK case. In particular all attributes that correspond to CPU polarization. But since all real world kernels have SCHED_BOOK selected anyway this doesn't matter too much. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* | Merge branch 'driver-core-next' into Linux 3.2Greg Kroah-Hartman2012-01-061-3/+3
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | This resolves the conflict in the arch/arm/mach-s3c64xx/s3c6400.c file, and it fixes the build error in the arch/x86/kernel/microcode_core.c file, that the merge did not catch. The microcode_core.c patch was provided by Stephen Rothwell <sfr@canb.auug.org.au> who was invaluable in the merge issues involved with the large sysdev removal process in the driver-core tree. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| * cpu: convert 'cpu' and 'machinecheck' sysdev_class to a regular subsystemKay Sievers2011-12-211-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This moves the 'cpu sysdev_class' over to a regular 'cpu' subsystem and converts the devices to regular devices. The sysdev drivers are implemented as subsystem interfaces now. After all sysdev classes are ported to regular driver core entities, the sysdev implementation will be entirely removed from the kernel. Userspace relies on events and generic sysfs subsystem infrastructure from sysdev devices, which are made available with this conversion. Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Borislav Petkov <bp@amd64.org> Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk> Cc: Len Brown <lenb@kernel.org> Cc: Zhang Rui <rui.zhang@intel.com> Cc: Dave Jones <davej@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* | [S390] topology: fix topology on z10 machinesHeiko Carstens2011-11-141-7/+38
|/ | | | | | | | | Make sure that all cpus in a book on a z10 appear as book siblings and not as core siblings. This fixes some performance regressions that appeared after the book scheduling domain got introduced. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] topology: fix alloc_masks annotationSebastian Ott2011-10-301-2/+2
| | | | | | | | | Fix this warning: WARNING: vmlinux.o(.text+0x199b6): Section mismatch in reference from the function alloc_masks() to the function .init.text:__alloc_bootmem() Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] irq: merge irq.c and s390_ext.cHeiko Carstens2011-05-261-1/+0
| | | | | | | | Merge irq.c and s390_ext.c into irq.c. That way all external interrupt related functions are together. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] convert old cpumask API into new oneKOSAKI Motohiro2011-05-231-8/+8
| | | | | | | Adapt new API. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] topology: fix cpu masks for topology=off caseHeiko Carstens2010-10-291-2/+4
| | | | | | | | | | | | | Fix cpu masks for 'topology=off' case. Folding of the scheduling domains happen in such a way that everything belongs to the MC domain instead of the CPU doimain. This should fix a performance regression introduced with eafd2b6d "[S390] topology: use default MC domain initializer" and also makes sure we have the same behavious as if CONFIG_SCHED_MC was not selected at all. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] topology: export cpu topology via proc/sysinfoHeiko Carstens2010-10-251-2/+1
| | | | | | | | | | | | | | | | | Export the cpu configuration topology via sysinfo. Two new lines are introduced: CPU Topology HW: 0 0 0 4 6 4 CPU Topology SW: 0 0 0 0 4 24 The HW line describes the cpu topology nesting levels when the maximum nesting level is used to get the corresponding SYSIB. The SW line describes what Linux is actually using. In this case it supports only two levels (CONFIG_SCHED_BOOK off) and therefore the hardware folded the two lower levels in the SYSIB response block. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] topology: move topology sysinfo codeHeiko Carstens2010-10-251-54/+21
| | | | | | | | Move the topology sysinfo SYSIB definitions to the proper place in asm/sysinfo.h where they should be. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] topology: clean up facility detectionHeiko Carstens2010-10-251-9/+5
| | | | | | | | Move cpu topology facility detection to early setup code where it should be. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] cleanup facility list handlingMartin Schwidefsky2010-10-251-4/+1
| | | | | | | Store the facility list once at system startup with stfl/stfle and reuse the result for all facility tests. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] topology: change defaultHeiko Carstens2010-10-251-3/+3
| | | | | | | | | Switch default value of the kernel parameter 'topology' from off to on. Various performance measurements have finally shown that there are no (known) regressions anywhere. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* topology, s390: Add z11 cpu topology supportHeiko Carstens2010-09-091-57/+93
| | | | | | | | | | Use the extended cpu topology information that z11 machines provide to improve the scheduler's decision making. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100831082844.604956770@de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* [S390] topology: expose core identifierHeiko Carstens2010-05-171-1/+6
| | | | | | | | | Provide a topology_core_id define which makes sure that the contents of /sys/devices/system/cpu/cpuX/topology/core_id indeed do contain the core id and not always 0. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] arch/s390/kernel: Add missing unlockJulia Lawall2010-04-091-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | In the default case the lock is not unlocked. The return is converted to a goto, to share the unlock at the end of the function. A simplified version of the semantic patch that finds this problem is as follows: (http://coccinelle.lip6.fr/) // <smpl> @r exists@ expression E1; identifier f; @@ f (...) { <+... * spin_lock_irq (E1,...); ... when != E1 * return ...; ...+> } // </smpl> Signed-off-by: Julia Lawall <julia@diku.dk> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] Move __cpu_logical_map to smp.cHeiko Carstens2010-01-131-1/+1
| | | | | | | | Finally move it to the place where it belongs to and make get rid of it for !CONFIG_SMP. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] cpumask: remove cpu_coregroup_mapRusty Russell2009-03-261-1/+1
| | | | | | | | | | | Impact: cleanup cpu_coregroup_mask is the New Hotness. As S/390 uses theirs internally, so we just make it static. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* Merge branch 'master' of ↵Rusty Russell2008-12-301-24/+22
|\ | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
| * Merge branch 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6Linus Torvalds2008-12-281-22/+19
| |\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6: (85 commits) [S390] provide documentation for hvc_iucv kernel parameter. [S390] convert ctcm printks to dev_xxx and pr_xxx macros. [S390] convert zfcp printks to pr_xxx macros. [S390] convert vmlogrdr printks to pr_xxx macros. [S390] convert zfcp dumper printks to pr_xxx macros. [S390] convert cpu related printks to pr_xxx macros. [S390] convert qeth printks to dev_xxx and pr_xxx macros. [S390] convert sclp printks to pr_xxx macros. [S390] convert iucv printks to dev_xxx and pr_xxx macros. [S390] convert ap_bus printks to pr_xxx macros. [S390] convert dcssblk and extmem printks messages to pr_xxx macros. [S390] convert monwriter printks to pr_xxx macros. [S390] convert s390 debug feature printks to pr_xxx macros. [S390] convert monreader printks to pr_xxx macros. [S390] convert appldata printks to pr_xxx macros. [S390] convert setup printks to pr_xxx macros. [S390] convert hypfs printks to pr_xxx macros. [S390] convert time printks to pr_xxx macros. [S390] convert cpacf printks to pr_xxx macros. [S390] convert cio printks to pr_xxx macros. ...
| | * [S390] convert cpu related printks to pr_xxx macros.Martin Schwidefsky2008-12-251-1/+4
| | | | | | | | | | | | Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| | * [S390] cpu topology: remove dead codeHeiko Carstens2008-12-251-18/+1
| | | | | | | | | | | | | | | | | | | | | Interrupts haven't been implemented. So remove the dead code. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| | * [S390] cpu topology: introduce kernel parameterHeiko Carstens2008-12-251-1/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce a topology=[on|off] kernel parameter which allows to switch cpu topology on/off. Default will be off, since it looks like that for some workloards this doesn't behave very well (on s390). Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| | * [S390] cpu topology: dont destroy cpu sets on topology changeHeiko Carstens2008-12-251-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Call rebuild_sched_domains instead of arch_reinit_sched_domains if cpu topology changes. This leaves cpu sets alone which otherwise would be destroyed. If and how it makes sense to define cpu sets on a virtualized architecture is another question. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| | * [S390] cpu topology: fix cpu_core_map initializationHeiko Carstens2008-12-251-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Common code doesn't call arch_update_cpu_topology() anymore on cpu hotplug. But our architecture backend relied on that in order to update the cpu_core_map. For machines without cpu topology support this leads uninitialized cpu_core_maps for later on added cpus. To solve this just initialize the maps with cpu_possible_map, since that will be always valid for machines without topology support. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| * | sched: let arch_update_cpu_topology indicate if topology changedHeiko Carstens2008-12-121-2/+3
| |/ | | | | | | | | | | | | | | | | Change arch_update_cpu_topology so it returns 1 if the cpu topology changed and 0 if it didn't change. This will be useful for the next patch which adds a call to this function in partition_sched_domains. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* / cpumask: cpu_coregroup_mask(): s390Rusty Russell2008-12-261-0/+5
|/ | | | | | | | | Like cpu_coregroup_map, but returns a (const) pointer. Compile-tested on s390 (defconfig). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Mike Travis <travis@sgi.com>
* [S390] cpu topology: fix lockingHeiko Carstens2008-11-141-4/+7
| | | | | | | | | | | | | | | | cpu_coregroup_map used to grab a mutex on s390 since it was only called from process context. Since c7c22e4d5c1fdebfac4dba76de7d0338c2b0d832 "block: add support for IO CPU affinity" this is not true anymore. It now also gets called from softirq context. To prevent possible deadlocks change this in architecture code and use a spinlock instead of a mutex. Cc: stable@kernel.org Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* S390 topology: don't use kthread() for arch_reinit_sched_domains()Oleg Nesterov2008-07-251-13/+1
| | | | | | | | | | | | | | | | | | | | | | Now that it is safe to use get_online_cpus() we can revert [S390] cpu topology: Fix possible deadlock. commit: fd781fa25c9e9c6fd1599df060b05e7c4ad724e5 and call arch_reinit_sched_domains() directly from topology_work_fn(). Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: Gautham R Shenoy <ego@in.ibm.com> Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Max Krasnyansky <maxk@qualcomm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Paul Menage <menage@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Vegard Nossum <vegard.nossum@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [S390] arch/s390: Eliminate NULL test and memset after alloc_bootmemJulia Lawall2008-07-141-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As noted by Akinobu Mita in patch b1fceac2b9e04d278316b2faddf276015fc06e3b, alloc_bootmem and related functions never return NULL and always return a zeroed region of memory. Thus a NULL test or memset after calls to these functions is unnecessary. arch/s390/kernel/topology.c | 2 -- 1 file changed, 2 deletions(-) This was fixed using the following semantic patch. (http://www.emn.fr/x-info/coccinelle/) // <smpl> @@ expression E; statement S; @@ E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...) ... when != E ( - BUG_ON (E == NULL); | - if (E == NULL) S ) @@ expression E,E1; @@ E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...) ... when != E - memset(E,0,E1); // </smpl> Signed-off-by: Julia Lawall <julia@diku.dk> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] cpu topology: Fix possible deadlock.Heiko Carstens2008-04-301-1/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When we get a notification that cpu topology changed, we schedule a work struct which just calls arch_reinit_sched_domains. This function in turn calls get_online_cpus() which results int the lockdep warning below. After all it turnded out that it's not legal to call get_online_cpus() from the context of a multi-threaded work queue. It could deadlock this way: process 0 (events/cpu-x): -> run_workqueue -> removes my work_struct from the work queue -> calls work_struct->fn -> get_online_cpus() -> locks on cpu_hotplug.lock since process 1 below is doing cpu hotplug process 1: -> cpu_down (for cpu-x) -> cpu_hotplug_begin (holds cpu_hotplug.lock now) -> cpu-x dead -> notifier_call_chain with CPU_DEAD -> cleanup_workqueue_thread -> flush_cpu_workqueue (succeeds) -> kthread_stop for events/cpu-x -> now kthread_stop waits for my work_struct to complete from within process 0. -> dead. A single threaded workqueue wouldn't have such problems, however there is no such common queue available and it's not worth to create one for the very rare calls to arch_reinit_sched_domains. So we just create a kernel thread from our work struct which calls arch_reinit_sched_domains and are done with it. Thanks to Oleg Nesterov and Peter Zijlstra for helping me figuring out that this isn't a false positive lockdep warning: ======================================================= [ INFO: possible circular locking dependency detected ] 2.6.25-03562-g3dc5063-dirty #12 ------------------------------------------------------- events/3/14 is trying to acquire lock: (&cpu_hotplug.lock){--..}, at: [<0000000000076094>] get_online_cpus+0x50/0x78 but task is already holding lock: (topology_work){--..}, at: [<0000000000059cde>] run_workqueue+0x106/0x278 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (topology_work){--..}: [<000000000006fc74>] __lock_acquire+0x1010/0x111c [<000000000006fe40>] lock_acquire+0xc0/0xf8 [<0000000000059d48>] run_workqueue+0x170/0x278 [<0000000000059edc>] worker_thread+0x8c/0xf0 [<000000000005f5bc>] kthread+0x68/0xa0 [<000000000001a33e>] kernel_thread_starter+0x6/0xc [<000000000001a338>] kernel_thread_starter+0x0/0xc -> #1 (events){--..}: [<000000000006fc74>] __lock_acquire+0x1010/0x111c [<000000000006fe40>] lock_acquire+0xc0/0xf8 [<000000000005a23c>] cleanup_workqueue_thread+0x60/0xa8 [<00000000003b2ab8>] workqueue_cpu_callback+0xbc/0x170 [<00000000003bba80>] notifier_call_chain+0x5c/0xa4 [<00000000000655a2>] __raw_notifier_call_chain+0x26/0x38 [<00000000000655e2>] raw_notifier_call_chain+0x2e/0x40 [<0000000000075e00>] cpu_down+0x228/0x31c [<00000000003b1dd8>] store_online+0x64/0xb8 [<00000000001e7128>] sysdev_store+0x48/0x58 [<0000000000121cd2>] sysfs_write_file+0x126/0x1c0 [<00000000000c1944>] vfs_write+0xb0/0x15c [<00000000000c20e6>] sys_write+0x56/0x88 [<0000000000027a68>] sys32_write+0x34/0x4c [<0000000000023f70>] sysc_noemu+0x10/0x16 [<0000000077f3f186>] 0x77f3f186 -> #0 (&cpu_hotplug.lock){--..}: [<000000000006fa84>] __lock_acquire+0xe20/0x111c [<000000000006fe40>] lock_acquire+0xc0/0xf8 [<00000000003b701c>] mutex_lock_nested+0xd0/0x364 [<0000000000076094>] get_online_cpus+0x50/0x78 [<000000000003a03e>] arch_reinit_sched_domains+0x26/0x58 [<000000000002700e>] topology_work_fn+0x26/0x34 [<0000000000059d4e>] run_workqueue+0x176/0x278 [<0000000000059edc>] worker_thread+0x8c/0xf0 [<000000000005f5bc>] kthread+0x68/0xa0 [<000000000001a33e>] kernel_thread_starter+0x6/0xc [<000000000001a338>] kernel_thread_starter+0x0/0xc other info that might help us debug this: 2 locks held by events/3/14: #0: (events){--..}, at: [<0000000000059cde>] run_workqueue+0x106/0x278 #1: (topology_work){--..}, at: [<0000000000059cde>] run_workqueue+0x106/0x278 stack backtrace: CPU: 3 Not tainted 2.6.25-03562-g3dc5063-dirty #12 Process events/3 (pid: 14, task: 000000002fb04038, ksp: 000000002fb0bd70) 0400000000000000 000000002fb0ba40 0000000000000002 0000000000000000 000000002fb0bae0 000000002fb0ba58 000000002fb0ba58 0000000000016488 0000000000000000 000000002fb0bd70 0000000000000000 0000000000000000 000000002fb0ba40 000000000000000c 000000002fb0ba40 000000002fb0bab0 00000000003c99e0 0000000000016488 000000002fb0ba40 000000002fb0ba90 Call Trace: ([<00000000000163fc>] show_trace+0x138/0x158) [<00000000000164e2>] show_stack+0xc6/0xf8 [<0000000000016624>] dump_stack+0xb0/0xc0 [<000000000006cd36>] print_circular_bug_tail+0xa2/0xb4 [<000000000006fa84>] __lock_acquire+0xe20/0x111c [<000000000006fe40>] lock_acquire+0xc0/0xf8 [<00000000003b701c>] mutex_lock_nested+0xd0/0x364 [<0000000000076094>] get_online_cpus+0x50/0x78 [<000000000003a03e>] arch_reinit_sched_domains+0x26/0x58 [<000000000002700e>] topology_work_fn+0x26/0x34 [<0000000000059d4e>] run_workqueue+0x176/0x278 [<0000000000059edc>] worker_thread+0x8c/0xf0 [<000000000005f5bc>] kthread+0x68/0xa0 [<000000000001a33e>] kernel_thread_starter+0x6/0xc [<000000000001a338>] kernel_thread_starter+0x0/0xc INFO: lockdep is turned off. Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* [S390] Add topology_core_siblings to topology.hHeiko Carstens2008-04-301-3/+18
| | | | | | This exposes the core siblings to user space via sysfs. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
* [S390] Vertical cpu management.Heiko Carstens2008-04-171-15/+57
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If vertical cpu polarization is active then the hypervisor will dispatch certain cpus for a longer time than other cpus for maximum performance. For example if a guest would have three virtual cpus, each of them with a share of 33 percent, then in case of vertical cpu polarization all of the processing time would be combined to a single cpu which would run all the time, while the other two cpus would get nearly no cpu time. There are three different types of vertical cpus: high, medium and low. Low cpus hardly get any real cpu time, while high cpus get a full real cpu. Medium cpus get something in between. In order to switch between the two possible modes (default is horizontal) a 0 for horizontal polarization or a 1 for vertical polarization must be written to the dispatching sysfs attribute: /sys/devices/system/cpu/dispatching The polarization of each single cpu can be figured out by the polarization sysfs attribute of each cpu: /sys/devices/system/cpu/cpuX/polarization horizontal, vertical:high, vertical:medium, vertical:low or unknown. When switching polarization the polarization attribute may contain the value unknown until the configuration change is done and the kernel has figured out the new polarization of each cpu. Note that running a system with different types of vertical cpus may result in significant performance regressions. If possible only one type of vertical cpus should be used. All other cpus should be offlined. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
* [S390] cpu topology support for s390.Heiko Carstens2008-04-171-0/+272
Add s390 backend so we can give the scheduler some hints about the cpu topology. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
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