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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4DD3C433FE for ; Fri, 25 Mar 2022 08:54:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355951AbiCYI4C (ORCPT ); Fri, 25 Mar 2022 04:56:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39740 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354281AbiCYI4B (ORCPT ); Fri, 25 Mar 2022 04:56:01 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7755F44A2D; Fri, 25 Mar 2022 01:54:27 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 391C8B824E8; Fri, 25 Mar 2022 08:54:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3BD4CC340E9; Fri, 25 Mar 2022 08:54:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1648198464; bh=9hytOMtTOBnafBj5UxposoR8sC86nfCae0S2BSIC3hM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wNUhdvTywTFzC542loW+OvSYeepuTylRZfUgMu8VlO4ChLnSkGn6gkQo/+C8uCDPB TtEavdYBU4LpEwsdAhQpYf0Rmw7I7K9YXr62HghI3C87sh1sQCXrbmt9HG9UhWGLwR t/u9tGCkenb16ERR3bQm1rCaAFCPSf6W2F74R9QY= Date: Fri, 25 Mar 2022 09:54:21 +0100 From: Greg KH To: Karel Zak Cc: Miklos Szeredi , Theodore Ts'o , Christian Brauner , Miklos Szeredi , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Linux API , linux-man , LSM , Ian Kent , David Howells , Linus Torvalds , Al Viro , Christian Brauner , Amir Goldstein , James Bottomley Subject: Re: [RFC PATCH] getvalues(2) prototype Message-ID: References: <20220322192712.709170-1-mszeredi@redhat.com> <20220323114215.pfrxy2b6vsvqig6a@wittgenstein> <20220325084646.7g6oto2ce3vou54x@ws.net.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220325084646.7g6oto2ce3vou54x@ws.net.home> Precedence: bulk List-ID: On Fri, Mar 25, 2022 at 09:46:46AM +0100, Karel Zak wrote: > On Thu, Mar 24, 2022 at 09:44:38AM +0100, Miklos Szeredi wrote: > > > If so, have you benchmarked lsof using this new interface? > > > > Not yet. Looked yesterday at both lsof and procps source code, and > > both are pretty complex and not easy to plug in a new interface. But > > I've not yet given up... > > I can imagine something like getvalues(2) in lsblk (based on /sys) or > in lsfd (based on /proc; lsof replacement). The tools have defined set > of information to read from kernel, so gather all the requests to the > one syscall for each process or block device makes sense and it will > dramatically reduce number of open+read+close syscalls. And do those open+read+close syscalls actually show up in measurements? Again, I tried to find a real-world application that turning those 3 into 1 would matter, and I couldn't. procps had no decreased system load that I could notice. I'll mess with lsof but that's really just a stress-test, not anything that is run all the time, right? And as others have said, using io_uring() would also solve the 3 syscall issue, but no one seems to want to convert these tools to use that, which implies that it's not really an issue for anyone :) thanks, greg k-h