linux-kernel - Re: [PATCH] xfs: Use xchg() in xlog_cil_insert_pcp

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Message-Id: <173279636431.817822.13565572630858949349.b4-ty@kernel.org>
Date: Thu, 28 Nov 2024 13:19:24 +0100
From: Carlos Maiolino <cem@...nel.org>
To: linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Uros Bizjak <ubizjak@...il.com>
Cc: Chandan Babu R <chandan.babu@...cle.com>, 
 "Darrick J. Wong" <djwong@...nel.org>, 
 Christoph Hellwig <hch@...radead.org>, Dave Chinner <dchinner@...hat.com>
Subject: Re: [PATCH] xfs: Use xchg() in xlog_cil_insert_pcp_aggregate()

On Wed, 20 Nov 2024 16:06:22 +0100, Uros Bizjak wrote:
> try_cmpxchg() loop with constant "new" value can be substituted
> with just xchg() to atomically get and clear the location.
> 
> The code on x86_64 improves from:
> 
>     1e7f:	48 89 4c 24 10       	mov    %rcx,0x10(%rsp)
>     1e84:	48 03 14 c5 00 00 00 	add    0x0(,%rax,8),%rdx
>     1e8b:	00
> 			1e88: R_X86_64_32S	__per_cpu_offset
>     1e8c:	8b 02                	mov    (%rdx),%eax
>     1e8e:	41 89 c5             	mov    %eax,%r13d
>     1e91:	31 c9                	xor    %ecx,%ecx
>     1e93:	f0 0f b1 0a          	lock cmpxchg %ecx,(%rdx)
>     1e97:	75 f5                	jne    1e8e <xlog_cil_commit+0x84e>
>     1e99:	48 8b 4c 24 10       	mov    0x10(%rsp),%rcx
>     1e9e:	45 01 e9             	add    %r13d,%r9d
> 
> [...]

Applied to for-next, thanks!

[1/1] xfs: Use xchg() in xlog_cil_insert_pcp_aggregate()
      commit: 214093534f3c046bf5acc9affbf4e6bd9af4538b

Best regards,
-- 
Carlos Maiolino <cem@...nel.org>