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b=h3DJE3uzr5u7e5QlVRfuaMKdOWZCSS0y+aO+RSY9Q1RBs64syNXhN5i0mJdqx5L5z L4bzGegkyXJQdAk+WUTXY6Cydiv56sHJCiyQo31qChuuPTtkDjIMsEk+Vz3Kiszvc1 hc9kNBvLjjtW8wYMvadv+JsO1B5UDzUqV6fhc4AA= Date: Fri, 30 Aug 2024 17:33:38 -0700 From: Andrew Morton To: Adrian Huang Cc: Uladzislau Rezki , Christoph Hellwig , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Adrian Huang Subject: Re: [PATCH 1/1] mm: vmalloc: Optimize vmap_lazy_nr arithmetic when purging each vmap_area Message-Id: <20240830173338.20c174604ebd8807405a0908@linux-foundation.org> In-Reply-To: <20240829130633.2184-1-ahuang12@lenovo.com> References: <20240829130633.2184-1-ahuang12@lenovo.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 276F1A0024 X-Stat-Signature: 4x8h5u58x1estjtnxu9n8dsje67tnwwb X-Rspam-User: X-HE-Tag: 1725064419-978336 X-HE-Meta: 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 pvR0GBgg 4c0QJHSdT5vdch+bOScHA+HQ4d9Hd26dNU0ei9ZzJr0x9nwUln3ePVpYIZbtHo+K0BowBExRSJuF3GTbF9BBg+VLaCp13cCijHubOWfHfoqGiKIvezbr5ajqwY/2HDFLxI0dy7MNj6xN2y2oAV14Af8FYD9/nzOzn0DeTDilF2DFhfROM0ZuZwc0e2DKEpc1FKzoPn8EuErsGtjvUcbdiwKx9KBiSJttubrwiimCy1c7IfTZhw4RNCvZJCvzXADeAGkq0ee9CaTKoUZxG1zfUENIQ0w6oToHD3xrJsKCXTBTN9tNlm43EA5/7XStJJxl3ccAjutdAAxAcjQa0uCEhtBSvMQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 29 Aug 2024 21:06:33 +0800 Adrian Huang wrote: > From: Adrian Huang > > When running the vmalloc stress on a 448-core system, observe the average > latency of purge_vmap_node() is about 2 seconds by using the eBPF/bcc > 'funclatency.py' tool [1]. > > ... > > 3) The data in column "w/o patch" and "w/ patch" > * Unit: micro seconds (us) > * Each data is the average of 3-time measurements > > System w/o patch (us) w/ patch (us) Improvement (%) > --------------- -------------- ------------- ------------- > 72-core server 2194 14 99.36% > 192-core server 143799 1139 99.21% > 448-core server 1992122 6883 99.65% > Holy cow. I'll add cc:stable to this. Partly because it fixes a softlockup, partly because holy cow.