From: Ingo Molnar <mingo@kernel.org>
To: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc: Andy Lutomirski <luto@amacapital.net>,
Andrew Morton <akpm@linux-foundation.org>,
Denys Vlasenko <dvlasenk@redhat.com>,
Brian Gerst <brgerst@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Waiman Long <Waiman.Long@hp.com>
Subject: Re: [RFC PATCH 00/12] x86/mm: Implement lockless pgd_alloc()/pgd_free()
Date: Thu, 11 Jun 2015 16:13:53 +0200 [thread overview]
Message-ID: <20150611141353.GA9447@gmail.com> (raw)
In-Reply-To: <1434031637-9091-1-git-send-email-mingo@kernel.org>
[ I fat-fingered the linux-mm Cc:, so every reply will bounce on that,
sorry about that :-/ Fixed it in this mail's Cc: list. ]
* Ingo Molnar <mingo@kernel.org> wrote:
> Waiman Long reported 'pgd_lock' contention on high CPU count systems and
> proposed moving pgd_lock on a separate cacheline to eliminate false sharing and
> to reduce some of the lock bouncing overhead.
So 'pgd_lock' is a global lock, used for every new task creation:
arch/x86/mm/fault.c:DEFINE_SPINLOCK(pgd_lock);
which with a sufficiently high CPU count starts to hurt.
Thanks,
Ingo
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parent reply other threads:[~2015-06-11 14:14 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <1434031637-9091-1-git-send-email-mingo@kernel.org>]
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