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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id e13-v6sm7512328wrm.45.2018.06.21.07.31.41 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 21 Jun 2018 07:31:42 -0700 (PDT) Date: Thu, 21 Jun 2018 16:31:40 +0200 From: Ingo Molnar To: Mike Snitzer Cc: Thomas Gleixner , Mikulas Patocka , Dan Williams , device-mapper development , X86 ML , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 RESEND] x86: optimize memcpy_flushcache Message-ID: <20180621143140.GA14095@gmail.com> References: <20180519052503.325953342@debian.vm> <20180519052631.730455475@debian.vm> <20180524182013.GA59755@redhat.com> <20180618132306.GA25431@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180618132306.GA25431@redhat.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Mike Snitzer wrote: > From: Mikulas Patocka > Subject: [PATCH v2] x86: optimize memcpy_flushcache > > In the context of constant short length stores to persistent memory, > memcpy_flushcache suffers from a 2% performance degradation compared to > explicitly using the "movnti" instruction. > > Optimize 4, 8, and 16 byte memcpy_flushcache calls to explicitly use the > movnti instruction with inline assembler. Linus requested asm optimizations to include actual benchmarks, so it would be nice to describe how this was tested, on what hardware, and what the before/after numbers are. Thanks, Ingo