From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3FF71C433DB for ; Wed, 24 Feb 2021 11:28:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A392764E90 for ; Wed, 24 Feb 2021 11:28:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A392764E90 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F361E6B0006; Wed, 24 Feb 2021 06:28:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EE54E6B006C; Wed, 24 Feb 2021 06:28:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DFB646B006E; Wed, 24 Feb 2021 06:28:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0067.hostedemail.com [216.40.44.67]) by kanga.kvack.org (Postfix) with ESMTP id CBDA76B0006 for ; Wed, 24 Feb 2021 06:28:32 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 96409A2A4 for ; Wed, 24 Feb 2021 11:28:32 +0000 (UTC) X-FDA: 77852938464.30.766FFB9 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf12.hostedemail.com (Postfix) with ESMTP id 25A9EED for ; Wed, 24 Feb 2021 11:28:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614166111; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uKVLad2iARoW1c2dRwOltL8pSbyE/6ChbP13Q5obmTg=; b=f6IhKjWYhMtfBfvhbPQZy1onWlZF/EVkEjN2eq4kCwwiAQKPrhroLfYSTGEsAADPSHk5wD ACU/JeoTe3DGC/Kw16vb1AR0Saz4DZ6nYjqr1Jl+GKk35KlC8TYfFdfo12N6YYu0BHJeQA zfc9yDBvfvNWBoOvi+JR9IGGyK1tImA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-595-VNUKl0siP7qMYyLUDwGloA-1; Wed, 24 Feb 2021 06:27:31 -0500 X-MC-Unique: VNUKl0siP7qMYyLUDwGloA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 349E6104ED67; Wed, 24 Feb 2021 11:27:30 +0000 (UTC) Received: from carbon (unknown [10.36.110.51]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7922360C5F; Wed, 24 Feb 2021 11:27:24 +0000 (UTC) Date: Wed, 24 Feb 2021 12:27:23 +0100 From: Jesper Dangaard Brouer To: Mel Gorman Cc: Chuck Lever , LKML , Linux-Net , Linux-MM , Linux-NFS , brouer@redhat.com Subject: Re: [RFC PATCH 0/3] Introduce a bulk order-0 page allocator for sunrpc Message-ID: <20210224122723.15943e95@carbon> In-Reply-To: <20210224102603.19524-1-mgorman@techsingularity.net> References: <20210224102603.19524-1-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 25A9EED X-Stat-Signature: 6z49sx7bhsdbn5cri3bgrhb4p5j94js5 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf12; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614166105-897490 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: On Wed, 24 Feb 2021 10:26:00 +0000 Mel Gorman wrote: > This is a prototype series that introduces a bulk order-0 page allocator > with sunrpc being the first user. The implementation is not particularly > efficient and the intention is to iron out what the semantics of the API > should be. That said, sunrpc was reported to have reduced allocation > latency when refilling a pool. I also have a use-case in page_pool, and I've been testing with the earlier patches, results are here[1] [1] https://github.com/xdp-project/xdp-project/blob/master/areas/mem/page_pool06_alloc_pages_bulk.org Awesome to see this newer patchset! thanks a lot for working on this! I'll run some new tests based on this. > As a side-note, while the implementation could be more efficient, it > would require fairly deep surgery in numerous places. The lock scope would > need to be significantly reduced, particularly as vmstat, per-cpu and the > buddy allocator have different locking protocol that overal -- e.g. all > partially depend on irqs being disabled at various points. Secondly, > the core of the allocator deals with single pages where as both the bulk > allocator and per-cpu allocator operate in batches. All of that has to > be reconciled with all the existing users and their constraints (memory > offline, CMA and cpusets being the trickiest). As you can see in[1], I'm getting a significant speedup from this. I guess that the cost of finding the "zone" is higher than I expected, as this basically what we/you amortize for the bulk. > In terms of semantics required by new users, my preference is that a pair > of patches be applied -- the first which adds the required semantic to > the bulk allocator and the second which adds the new user. > > Patch 1 of this series is a cleanup to sunrpc, it could be merged > separately but is included here for convenience. > > Patch 2 is the prototype bulk allocator > > Patch 3 is the sunrpc user. Chuck also has a patch which further caches > pages but is not included in this series. It's not directly > related to the bulk allocator and as it caches pages, it might > have other concerns (e.g. does it need a shrinker?) > > This has only been lightly tested on a low-end NFS server. It did not break > but would benefit from an evaluation to see how much, if any, the headline > performance changes. The biggest concern is that a light test case showed > that there are a *lot* of bulk requests for 1 page which gets delegated to > the normal allocator. The same criteria should apply to any other users. If you change local_irq_save(flags) to local_irq_disable() then you can likely get better performance for 1 page requests via this API. This limits the API to be used in cases where IRQs are enabled (which is most cases). (For my use-case I will not do 1 page requests). -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer