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| author | Paul Menage <menage@google.com> | 2009-01-29 14:25:21 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-29 18:04:45 -0800 |
| commit | 804b3c28a4e4fa1c224571bf76edb534b9c4b1ed (patch) | |
| tree | 59e0dabb227a5067cfdc7cce13f149f141ef8cb4 /kernel/cgroup.c | |
| parent | 1404f06565ee89e0ce04d4a5859c00b0e3a0dc8d (diff) | |
| download | linux-804b3c28a4e4fa1c224571bf76edb534b9c4b1ed.tar.gz linux-804b3c28a4e4fa1c224571bf76edb534b9c4b1ed.tar.bz2 linux-804b3c28a4e4fa1c224571bf76edb534b9c4b1ed.zip | |
cgroups: add cpu_relax() calls in css_tryget() and cgroup_clear_css_refs()
css_tryget() and cgroup_clear_css_refs() contain polling loops; these
loops should have cpu_relax calls in them to reduce cross-cache traffic.
Signed-off-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 0066092de19a..492215d67fa5 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2509,7 +2509,7 @@ static int cgroup_clear_css_refs(struct cgroup *cgrp) for_each_subsys(cgrp->root, ss) { struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; int refcnt; - do { + while (1) { /* We can only remove a CSS with a refcnt==1 */ refcnt = atomic_read(&css->refcnt); if (refcnt > 1) { @@ -2523,7 +2523,10 @@ static int cgroup_clear_css_refs(struct cgroup *cgrp) * css_tryget() to spin until we set the * CSS_REMOVED bits or abort */ - } while (atomic_cmpxchg(&css->refcnt, refcnt, 0) != refcnt); + if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt) + break; + cpu_relax(); + } } done: for_each_subsys(cgrp->root, ss) { |