From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Michael Ellerman <mpe@ellerman.id.au>,
x86@kernel.org, linux-fsdevel@vger.kernel.org,
linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org
Subject: Re: remove the last set_fs() in common code, and remove it for x86 and powerpc
Date: Tue, 18 Aug 2020 20:23:12 +0200 [thread overview]
Message-ID: <e3781661-2e13-4f46-d892-181907a2e768@csgroup.eu> (raw)
In-Reply-To: <20200818180555.GA29185@lst.de>
Le 18/08/2020 à 20:05, Christoph Hellwig a écrit :
> On Tue, Aug 18, 2020 at 07:46:22PM +0200, Christophe Leroy wrote:
>> I gave it a go on my powerpc mpc832x. I tested it on top of my newest
>> series that reworks the 32 bits signal handlers (see
>> https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=196278) with
>> the microbenchmark test used is that series.
>>
>> With KUAP activated, on top of signal32 rework, performance is boosted as
>> system time for the microbenchmark goes from 1.73s down to 1.56s, that is
>> 10% quicker
>>
>> Surprisingly, with the kernel as is today without my signal's series, your
>> series degrades performance slightly (from 2.55s to 2.64s ie 3.5% slower).
>>
>>
>> I also observe, in both cases, a degradation on
>>
>> dd if=/dev/zero of=/dev/null count=1M
>>
>> Without your series, it runs in 5.29 seconds.
>> With your series, it runs in 5.82 seconds, that is 10% more time.
>
> That's pretty strage, I wonder if some kernel text cache line
> effects come into play here?
>
> The kernel access side is only used in slow path code, so it should
> not make a difference, and the uaccess code is simplified and should be
> (marginally) faster.
>
> Btw, was this with the __{get,put}_user_allowed cockup that you noticed
> fixed?
>
Yes it is with the __get_user_size() replaced by __get_user_size_allowed().
Christophe
next prev parent reply other threads:[~2020-08-18 18:23 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-17 7:32 remove the last set_fs() in common code, and remove it for x86 and powerpc Christoph Hellwig
2020-08-17 7:32 ` [PATCH 01/11] mem: remove duplicate ops for /dev/zero and /dev/null Christoph Hellwig
2020-08-18 19:33 ` Kees Cook
2020-08-17 7:32 ` [PATCH 02/11] fs: don't allow kernel reads and writes without iter ops Christoph Hellwig
2020-08-18 19:34 ` Kees Cook
2020-08-17 7:32 ` [PATCH 03/11] fs: don't allow splice read/write without explicit ops Christoph Hellwig
2020-08-18 19:39 ` Kees Cook
2020-08-18 19:54 ` Christoph Hellwig
2020-08-18 19:58 ` Kees Cook
2020-08-18 20:07 ` Christoph Hellwig
2020-08-17 7:32 ` [PATCH 04/11] uaccess: add infrastructure for kernel builds with set_fs() Christoph Hellwig
2020-08-18 19:40 ` Kees Cook
2020-08-17 7:32 ` [PATCH 05/11] test_bitmap: skip user bitmap tests for !CONFIG_SET_FS Christoph Hellwig
2020-08-17 7:50 ` Christophe Leroy
2020-08-17 7:52 ` Christoph Hellwig
2020-08-18 19:43 ` Kees Cook
2020-08-17 7:32 ` [PATCH 06/11] lkdtm: disable set_fs-based " Christoph Hellwig
2020-08-18 19:32 ` Kees Cook
2020-08-17 7:32 ` [PATCH 07/11] x86: move PAGE_OFFSET, TASK_SIZE & friends to page_{32,64}_types.h Christoph Hellwig
2020-08-18 19:27 ` Kees Cook
2020-08-17 7:32 ` [PATCH 08/11] x86: make TASK_SIZE_MAX usable from assembly code Christoph Hellwig
2020-08-18 19:44 ` Kees Cook
2020-08-18 19:55 ` Christoph Hellwig
2020-08-18 19:59 ` Kees Cook
2020-08-18 20:00 ` Christoph Hellwig
2020-08-18 20:08 ` Kees Cook
2020-08-17 7:32 ` [PATCH 09/11] x86: remove address space overrides using set_fs() Christoph Hellwig
2020-08-17 8:23 ` David Laight
2020-08-27 9:37 ` 'Christoph Hellwig'
2020-08-18 19:46 ` Kees Cook
2020-08-17 7:32 ` [PATCH 10/11] powerpc: use non-set_fs based maccess routines Christoph Hellwig
2020-08-17 15:47 ` Christophe Leroy
2020-08-17 7:32 ` [PATCH 11/11] powerpc: remove address space overrides using set_fs() Christoph Hellwig
2020-08-17 7:39 ` remove the last set_fs() in common code, and remove it for x86 and powerpc Christoph Hellwig
2020-08-18 17:46 ` Christophe Leroy
2020-08-18 18:05 ` Christoph Hellwig
2020-08-18 18:23 ` Christophe Leroy [this message]
2020-08-19 7:16 ` Christophe Leroy
2020-08-19 7:22 ` iter and normal ops on /dev/zero & co, was " Christoph Hellwig
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