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Wed, 03 Jul 2024 15:01:50 +0000 Message-ID: <792eeb90-90ba-4750-ab22-622023967eeb@suse.de> Date: Wed, 3 Jul 2024 17:01:49 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/4] nvme-tcp: switch to 'cpu' affinity scope for unbound workqueues Content-Language: en-US To: Sagi Grimberg , Hannes Reinecke Cc: Christoph Hellwig , Keith Busch , linux-nvme@lists.infradead.org References: <20240703135021.34143-1-hare@kernel.org> <20240703135021.34143-5-hare@kernel.org> <1259766c-234e-4958-a16f-9de753a4a0b5@grimberg.me> From: Hannes Reinecke In-Reply-To: <1259766c-234e-4958-a16f-9de753a4a0b5@grimberg.me> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 692D32128B X-Spamd-Result: default: False [-4.50 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; XM_UA_NO_VERSION(0.01)[]; MX_GOOD(-0.01)[]; RCVD_TLS_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCPT_COUNT_FIVE(0.00)[5]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,suse.de:dkim]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Action: no action X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240703_080152_162408_97C0409B X-CRM114-Status: GOOD ( 15.58 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 7/3/24 16:22, Sagi Grimberg wrote: > > > On 03/07/2024 16:50, Hannes Reinecke wrote: >> We should switch to the 'cpu' affinity scope when using the 'wq_unbound' >> parameter as this allows us to keep I/O locality and improve performance. > > Can you please describe more why this is better? locality between what? > Well; the default unbound scope is 'cache', which groups the cpu according to the cache hierarchy. I want the cpu locality of the workqueue items to be preserved as much as possible, so I switched to 'cpu' here. I'll get some performance numbers. > While you mention in your cover letter "comments and reviews are welcome" > The change logs in your patches are not designed to assist your reviewer. I spent the last few weeks trying to come up with a solution based on my original submission, but in the end I gave up as I hadn't been able to fix the original issue. This here is a different approach by massaging the 'wq_unbound' mechanism, which is not only easier but also has the big advantage that it actually works :-) So I did not include a changlog to the previous patchset as this is a pretty different approach. Sorry if this is confusing. Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich