From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dave Hansen <dave.hansen@intel.com>
Subject: Re: [PATCH v2 0/5] locking: Introduce local{,64}_try_cmpxchg
Date: Wed, 5 Apr 2023 09:37:04 -0700
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To: Uros Bizjak <ubizjak@gmail.com>, linux-alpha@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Richard Henderson <richard.henderson@linaro.org>, Ivan Kokshaysky <ink@jurassic.park.msu.ru>, Matt Turner <mattst88@gmail.com>, Huacai Chen <chenhuacai@kernel.org>, WANG Xuerui <kernel@xen0n.name>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>, Michael Ellerman <mpe@ellerman.id.au>, Nicholas Piggin <npiggin@gmail.com>, Christophe Leroy <christophe.leroy@csgroup.eu>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>, "H. Peter Anvin" <hpa@zytor.com>, Arnd Bergmann <arnd@arndb.de>, Peter Zijlstra <peterz@infradead.org>, Arnaldo Carvalho de Melo <acme@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Alexander Shishkin <alexander.shishkin@linux.intel.com>, Ji

On 4/5/23 07:17, Uros Bizjak wrote:
> Add generic and target specific support for local{,64}_try_cmpxchg
> and wire up support for all targets that use local_t infrastructure.

I feel like I'm missing some context.

What are the actual end user visible effects of this series?  Is there a
measurable decrease in perf overhead?  Why go to all this trouble for
perf?  Who else will use local_try_cmpxchg()?

I'm all for improving things, and perf is an important user.  But, if
the goal here is improving performance, it would be nice to see at least
a stab at quantifying the performance delta.