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From: Sasha Levin <sashal@kernel.org>
To: Nathan Chancellor <natechancellor@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Nick Desaulniers <ndesaulniers@google.com>,
	clang-built-linux@googlegroups.com
Subject: Re: Backport of commit a75bb4eb9e565b9f5115e2e8c07377ce32cbe69a
Date: Tue, 23 Apr 2019 15:35:12 -0400	[thread overview]
Message-ID: <20190423193512.GP17719@sasha-vm> (raw)
In-Reply-To: <20190423190426.18720-1-natechancellor@gmail.com>

On Tue, Apr 23, 2019 at 12:04:21PM -0700, Nathan Chancellor wrote:
>Hi Greg and Sasha,
>
>Please apply this commit to 4.4 through 5.0 (patches are threaded in
>reply to this one), which will prevent Clang from emitting references
>to compiler runtime functions and doing some performance-killing
>optimization when using CONFIG_CC_OPTIMIZE_FOR_SIZE.
>
>Please let me know if I did something wrong or if there are any
>objections.

This looks like a fix for a performance regression, which don't usually
end up in stable unless they are severe enough.

This patch looks simple enough, and seeing peterz on it suggests to me
that this was significant enough for someone to notice. Is this really
the case, or is this just one of those %0.01 performance regression
things?

--
Thanks,
Sasha

  parent reply	other threads:[~2019-04-23 19:35 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-23 19:04 Nathan Chancellor
2019-04-23 19:04 ` [PATCH 4.14] Revert "kbuild: use -Oz instead of -Os when using clang" Nathan Chancellor
2019-04-23 19:04 ` [PATCH 4.19] " Nathan Chancellor
2019-04-23 19:04 ` [PATCH 4.4] " Nathan Chancellor
2019-04-23 19:04 ` [PATCH 4.9] " Nathan Chancellor
2019-04-23 19:04 ` [PATCH 5.0] " Nathan Chancellor
2019-04-23 19:35 ` Sasha Levin [this message]
2019-04-23 19:42   ` Backport of commit a75bb4eb9e565b9f5115e2e8c07377ce32cbe69a Nick Desaulniers
2019-04-23 19:45   ` Nathan Chancellor
2019-04-23 19:56     ` Matthias Kaehlcke
2019-04-23 20:03       ` Nathan Chancellor
2019-04-23 23:46         ` Sasha Levin
2019-04-24  5:58           ` Sedat Dilek

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