From: Manfred Spraul <manfred@colorfullife.com>
To: Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Davidlohr Bueso <dave@stgolabs.net>
Cc: LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
"H. Peter Anvin" <hpa@zytor.com>,
1vier1@web.de, felixh@informatik.uni-bremen.de,
Manfred Spraul <manfred@colorfullife.com>
Subject: [PATCH 0/2] ipc/sem.c: sem_lock fixes
Date: Sat, 1 Oct 2016 20:40:15 +0200 [thread overview]
Message-ID: <1475347217-2143-1-git-send-email-manfred@colorfullife.com> (raw)
Hi Andrew, Hi Peter, Hi Davidlohr,
New idea for ipc/sem:
The ACQUIRE from spin_lock() will continue to apply only for the load,
not for the store.
Thus: If we don't want to add arch dependencies into ipc/sem, the only
safe option is to use spin_lock()/spin_unlock() instead of spin_unlock_wait().
Or we must stay with the current code, which is a ~9% regression.
Thus:
- Patch 1 replaces spin_unlock_wait() with spin_lock()/spin_unlock() and
removes all memory barriers that are then unnecessary.
- Patch 2 adds the hysteresis code.
What do you think?
The patches passed stress-testing.
Andrew: Could you add it into mmots? Perhaps aiming for 4.10.
--
Manfred
next reply other threads:[~2016-10-01 18:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-01 18:40 Manfred Spraul [this message]
2016-10-01 18:40 ` [PATCH 1/2] ipc/sem.c: Avoid using spin_unlock_wait() Manfred Spraul
2016-10-01 18:40 ` [PATCH 2/2] ipc/sem: Add hysteresis Manfred Spraul
-- strict thread matches above, loose matches on Subject: below --
2016-07-13 5:06 [PATCH 0/2] ipc/sem.c: sem_lock fixes Manfred Spraul
2016-07-13 22:05 ` Andrew Morton
2016-07-14 16:40 ` Manfred Spraul
2016-06-25 17:37 Manfred Spraul
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