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60f3e00d25
Assign 'struct kern_ipc_perm' its own cacheline to avoid false sharing
with sysv ipc calls.
While the structure itself is rather read-mostly throughout the lifespan
of ipc, the spinlock causes most of the invalidations. One example is
commit 31a7c4746e9 ("ipc/sem.c: cacheline align the ipc spinlock for
semaphores"). Therefore, extend this to all ipc.
The effect of cacheline alignment on sems can be seen in sembench, which
deals mostly with semtimedop wait/wakes is seen to improve raw
throughput (worker loops) between 8 to 12% on a 24-core x86 with over 4
threads.
Link: http://lkml.kernel.org/r/1486673582-6979-4-git-send-email-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
26 lines
505 B
C
26 lines
505 B
C
#ifndef _LINUX_IPC_H
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#define _LINUX_IPC_H
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#include <linux/spinlock.h>
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#include <linux/uidgid.h>
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#include <uapi/linux/ipc.h>
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#define IPCMNI 32768 /* <= MAX_INT limit for ipc arrays (including sysctl changes) */
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/* used by in-kernel data structures */
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struct kern_ipc_perm {
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spinlock_t lock;
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bool deleted;
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int id;
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key_t key;
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kuid_t uid;
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kgid_t gid;
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kuid_t cuid;
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kgid_t cgid;
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umode_t mode;
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unsigned long seq;
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void *security;
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} ____cacheline_aligned_in_smp;
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#endif /* _LINUX_IPC_H */
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