From: Jon Masters <jcm@redhat.com>
To: Steve Capper <steve.capper@linaro.org>,
linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com,
linux@arm.linux.org.uk, linux-arch@vger.kernel.org,
linux-mm@kvack.org
Cc: will.deacon@arm.com, gary.robertson@linaro.org,
christoffer.dall@linaro.org, peterz@infradead.org,
anders.roxell@linaro.org, akpm@linux-foundation.org,
dann.frazier@canonical.com, mark.rutland@arm.com,
mgorman@suse.de, hughd@google.com
Subject: Re: [PATCH V4 0/6] RCU get_user_pages_fast and __get_user_pages_fast
Date: Fri, 27 Feb 2015 07:42:30 -0500 [thread overview]
Message-ID: <54F06636.6080905@redhat.com> (raw)
In-Reply-To: <1411740233-28038-1-git-send-email-steve.capper@linaro.org>
On 09/26/2014 10:03 AM, Steve Capper wrote:
> This series implements general forms of get_user_pages_fast and
> __get_user_pages_fast in core code and activates them for arm and arm64.
>
> These are required for Transparent HugePages to function correctly, as
> a futex on a THP tail will otherwise result in an infinite loop (due to
> the core implementation of __get_user_pages_fast always returning 0).
>
> Unfortunately, a futex on THP tail can be quite common for certain
> workloads; thus THP is unreliable without a __get_user_pages_fast
> implementation.
>
> This series may also be beneficial for direct-IO heavy workloads and
> certain KVM workloads.
>
> I appreciate that the merge window is coming very soon, and am posting
> this revision on the off-chance that it gets the nod for 3.18. (The changes
> thus far have been minimal and the feedback I've got has been mainly
> positive).
Head's up: these patches are currently implicated in a rare-to-trigger
hang that we are seeing on an internal kernel. An extensive effort is
underway to confirm whether these are the cause. Will followup.
Jon.
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next prev parent reply other threads:[~2015-02-27 12:43 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-26 14:03 [PATCH V4 0/6] RCU get_user_pages_fast and __get_user_pages_fast Steve Capper
2014-09-26 14:03 ` [PATCH V4 1/6] mm: Introduce a general RCU get_user_pages_fast Steve Capper
2014-09-29 21:51 ` Hugh Dickins
2014-10-01 11:11 ` Catalin Marinas
2014-10-02 16:00 ` Steve Capper
2014-10-02 12:19 ` Andrea Arcangeli
2014-10-02 16:18 ` Steve Capper
2014-10-02 16:54 ` Andrea Arcangeli
2014-10-13 5:15 ` Aneesh Kumar K.V
2014-10-13 5:21 ` David Miller
2014-10-13 11:44 ` Steve Capper
2014-10-13 16:06 ` David Miller
2014-10-14 12:38 ` Steve Capper
2014-10-14 16:30 ` David Miller
2014-10-13 17:04 ` Aneesh Kumar K.V
2014-10-13 6:22 ` Aneesh Kumar K.V
2014-09-26 14:03 ` [PATCH V4 2/6] arm: mm: Introduce special ptes for LPAE Steve Capper
2014-09-26 14:03 ` [PATCH V4 3/6] arm: mm: Enable HAVE_RCU_TABLE_FREE logic Steve Capper
2014-09-26 14:03 ` [PATCH V4 4/6] arm: mm: Enable RCU fast_gup Steve Capper
2014-09-26 14:03 ` [PATCH V4 5/6] arm64: mm: Enable HAVE_RCU_TABLE_FREE logic Steve Capper
2014-09-26 14:03 ` [PATCH V4 6/6] arm64: mm: Enable RCU fast_gup Steve Capper
2015-02-27 12:42 ` Jon Masters [this message]
2015-02-27 13:20 ` [PATCH V4 0/6] RCU get_user_pages_fast and __get_user_pages_fast Mark Rutland
2015-03-02 14:16 ` Mark Rutland
2015-03-02 2:10 ` PMD update corruption (sync question) Jon Masters
2015-03-02 5:58 ` Jon Masters
2015-03-02 10:50 ` Catalin Marinas
2015-03-02 11:06 ` Jon Masters
2015-03-02 12:31 ` Peter Zijlstra
2015-03-02 12:40 ` Geert Uytterhoeven
2015-03-02 22:21 ` Jon Masters
2015-03-02 22:29 ` Jon Masters
2015-03-03 9:06 ` Arnd Bergmann
2015-03-03 15:46 ` Jon Masters
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