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| author | David Mosberger-Tang <davidm@hpl.hp.com> | 2005-04-27 21:19:37 -0700 |
|---|---|---|
| committer | Tony Luck <tony.luck@intel.com> | 2005-04-27 21:19:37 -0700 |
| commit | 70929a57cfea8c18de13fcea9ae6771018a98949 (patch) | |
| tree | 1371e183617f368b7a92b185a2dee829c70d0efd /arch/ia64/kernel | |
| parent | f8fa5448fc9b4a7806b1297a0b57808f12fe4d43 (diff) | |
| download | linux-70929a57cfea8c18de13fcea9ae6771018a98949.tar.gz linux-70929a57cfea8c18de13fcea9ae6771018a98949.tar.bz2 linux-70929a57cfea8c18de13fcea9ae6771018a98949.zip | |
[IA64] Reschedule __kernel_syscall_via_epc().
Avoid some stalls, which is good for about 2 cycles when invoking a
light-weight handler. When invoking a heavy-weight handler, this
helps by about 7 cycles, with most of the improvement coming from the
improved branch-prediction achieved by splitting the BBB bundle into
two MIB bundles.
Signed-off-by: David Mosberger-Tang <davidm@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64/kernel')
| -rw-r--r-- | arch/ia64/kernel/gate.S | 31 |
1 files changed, 18 insertions, 13 deletions
diff --git a/arch/ia64/kernel/gate.S b/arch/ia64/kernel/gate.S index facf75acdc85..3cd3f2e971f6 100644 --- a/arch/ia64/kernel/gate.S +++ b/arch/ia64/kernel/gate.S @@ -79,31 +79,34 @@ GLOBAL_ENTRY(__kernel_syscall_via_epc) ;; rsm psr.be // note: on McKinley "rsm psr.be/srlz.d" is slightly faster than "rum psr.be" LOAD_FSYSCALL_TABLE(r14) - + ;; mov r16=IA64_KR(CURRENT) // 12 cycle read latency - tnat.nz p10,p9=r15 + shladd r18=r17,3,r14 mov r19=NR_syscalls-1 ;; - shladd r18=r17,3,r14 - - srlz.d - cmp.ne p8,p0=r0,r0 // p8 <- FALSE + lfetch [r18] // M0|1 + mov r29=psr // read psr (12 cyc load latency) /* Note: if r17 is a NaT, p6 will be set to zero. */ cmp.geu p6,p7=r19,r17 // (syscall > 0 && syscall < 1024+NR_syscalls)? ;; -(p6) ld8 r18=[r18] mov r21=ar.fpsr - add r14=-8,r14 // r14 <- addr of fsys_bubble_down entry + tnat.nz p10,p9=r15 + mov r26=ar.pfs ;; + srlz.d +(p6) ld8 r18=[r18] + nop.i 0 + ;; + nop.m 0 (p6) mov b7=r18 -(p6) tbit.z p8,p0=r18,0 +(p6) tbit.z.unc p8,p0=r18,0 + + nop.m 0 + nop.i 0 (p8) br.dptk.many b7 -(p6) rsm psr.i mov r27=ar.rsc - mov r26=ar.pfs - ;; - mov r29=psr // read psr (12 cyc load latency) +(p6) rsm psr.i /* * brl.cond doesn't work as intended because the linker would convert this branch * into a branch to a PLT. Perhaps there will be a way to avoid this with some @@ -111,6 +114,8 @@ GLOBAL_ENTRY(__kernel_syscall_via_epc) * instead. */ #ifdef CONFIG_ITANIUM + add r14=-8,r14 // r14 <- addr of fsys_bubble_down entry + ;; (p6) ld8 r14=[r14] // r14 <- fsys_bubble_down ;; (p6) mov b7=r14 |