From: Will Deacon <will.deacon@arm.com>
To: Steve Capper <steve.capper@linaro.org>
Cc: "linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Christoffer Dall <christoffer.dall@linaro.org>,
Russell King <linux@arm.linux.org.uk>,
Zi Shen Lim <zishen.lim@linaro.org>,
"patches@linaro.org" <patches@linaro.org>,
"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>
Subject: Re: [RFC PATCH 0/2] Implement get_user_pages_fast for ARM
Date: Tue, 29 Oct 2013 19:49:56 +0000 [thread overview]
Message-ID: <20131029194956.GC24556@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <1382101634-4723-1-git-send-email-steve.capper@linaro.org>
On Fri, Oct 18, 2013 at 02:07:11PM +0100, Steve Capper wrote:
> This patch series implements get_user_pages_fast on ARM. Unlike other
> architectures, we do not use IPIs/disabled IRQs as a blocking
> mechanism to protect the page table walker. Instead an atomic counter
> is used to indicate how many fast gup walkers are active on an address
> space, and any code that would cause them problems (THP splitting or
> code that could free a page table page) spins on positive values of
> this counter.
Curious: did you try benchmarking the two schemes? Whilst I expect this
algorithm to be better on ARM, exclusive memory accesses aren't free and
we're adding code to the fast path.
Will
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prev parent reply other threads:[~2013-10-29 19:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-18 13:07 [RFC PATCH 0/2] Implement get_user_pages_fast for ARM Steve Capper
2013-10-18 13:07 ` [RFC PATCH 1/2] thp: Introduce arch_(un)block_thp_split Steve Capper
2013-10-18 13:07 ` [RFC PATCH 2/2] arm: mm: implement get_user_pages_fast Steve Capper
2013-10-29 19:49 ` Will Deacon [this message]
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