From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: mm-commits@vger.kernel.org, senozhatsky@chromium.org,
ngupta@vflare.org, minchan@kernel.org, ubizjak@gmail.com
Subject: Re: + zram-use-try_cmpxchg-in-update_used_max.patch added to mm-unstable branch
Date: Wed, 26 Oct 2022 19:31:21 +0900 [thread overview]
Message-ID: <Y1kMeRsIX8kIKzpH@google.com> (raw)
In-Reply-To: <20221018205005.52F6CC433C1@smtp.kernel.org>
On (22/10/18 13:50), Andrew Morton wrote:
> Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in
> update_used_max. x86 CMPXCHG instruction returns success in ZF flag, so
> this change saves a compare after cmpxchg (and related move instruction in
> front of cmpxchg).
>
> Also, reorder code a bit to remove additional compare and conditional jump
> from the assembly code. Together, hese two changes save 15 bytes from the
> function when compiled for x86_64.
>
> No functional change intended.
>
> Link: https://lkml.kernel.org/r/20221018145154.3699-1-ubizjak@gmail.com
> Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Nitin Gupta <ngupta@vflare.org>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
I totally missed that patch.
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
prev parent reply other threads:[~2022-10-26 10:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-18 20:50 + zram-use-try_cmpxchg-in-update_used_max.patch added to mm-unstable branch Andrew Morton
2022-10-26 10:31 ` Sergey Senozhatsky [this message]
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