From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E4C21D12FE for ; Sat, 31 Aug 2024 00:33:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725064419; cv=none; b=uTgoeQUXShvlPWEAavS+KoLbn+y0z9QMCyZor/0doWKpJUkzqopyYZ12ciDZM11D9xOfmPPoksht2nWcYmq+INxtQh3tVwBUvqdhi+SSvR18O6x7LKkmiAsoadiknoDs5yRSnXKXFNYq7Kih9onZATcCUAfPQv95bOZ4VTrayIA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725064419; c=relaxed/simple; bh=/zwiYktsw8dhvsEPRVmjiwhged4kry9ZNXLHycg7zdA=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=KYmATqwdiHLb5sSCH1vuxTQvDobUCJ/CkIvi8MhZNVi/0g4Z+0aR2r8+NdPTIgasCKSnLI5HrxP1F53TVaIWoCJC5kToBHUC7u8YQLgSUzPJ+xeDHH0fgwo676YdaceLqgNGeyjQQe86AZreckeY+ZDcGxTVc24clnsmaq3XCwY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=h3DJE3uz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="h3DJE3uz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E3EBC4CEC2; Sat, 31 Aug 2024 00:33:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1725064418; bh=/zwiYktsw8dhvsEPRVmjiwhged4kry9ZNXLHycg7zdA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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.