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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5BDCAC02181 for ; Wed, 22 Jan 2025 20:17:20 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tah9a-0007AM-QB; Wed, 22 Jan 2025 15:16:47 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tah9G-00079H-P0 for qemu-devel@nongnu.org; Wed, 22 Jan 2025 15:16:32 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tah9C-0002Aj-0V for qemu-devel@nongnu.org; Wed, 22 Jan 2025 15:16:24 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1737576980; h=from:from:reply-to: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=9vCNqWs9ImXxipCSsenIHpvtvEMrfPIQD8+8bk/Q+Y0=; b=UFkGCbT+D5p0s41e6fee7rOGoGbT6o46I4CChh4aMWXzS22SHgeedTmnQlwhtwDTMfATXT AABiTSc5BLcvgxsL6+vpsV38cm5a3dd0xuKGUQuoxEXvhEiXF8fU0sjopKkCplPYPVj9Hy K22aZo2NB5bQ4bljU3fVERhHYBvhtC0= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-303-SjShgEKaOsmSpwQf8pWSgg-1; Wed, 22 Jan 2025 15:16:16 -0500 X-MC-Unique: SjShgEKaOsmSpwQf8pWSgg-1 X-Mimecast-MFC-AGG-ID: SjShgEKaOsmSpwQf8pWSgg Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CC6E91956068; Wed, 22 Jan 2025 20:16:13 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.43]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B459619560B7; Wed, 22 Jan 2025 20:16:10 +0000 (UTC) Date: Wed, 22 Jan 2025 20:16:07 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Michael Tokarev Cc: qemu-devel@nongnu.org, Thomas Huth , "Richard W.M. Jones" , qemu-stable Subject: Re: [PATCH] crypto: fix bogus error benchmarking pbkdf on fast machines Message-ID: References: <20250108184354.997818-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.13 (2024-03-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -50 X-Spam_score: -5.1 X-Spam_bar: ----- X-Spam_report: (-5.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.996, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Jan 22, 2025 at 10:19:41PM +0300, Michael Tokarev wrote: > 08.01.2025 21:43, Daniel P. Berrangé пишет: > > We're seeing periodic reports of errors like: > > > > $ qemu-img create -f luks --object secret,data=123456,id=sec0 \ > > -o key-secret=sec0 luks-info.img 1M > > Formatting 'luks-info.img', fmt=luks size=1048576 key-secret=sec0 > > qemu-img: luks-info.img: Unable to get accurate CPU usage > > > > This error message comes from a recent attempt to workaround a > > kernel bug with measuring rusage in long running processes: > > > > commit c72cab5ad9f849bbcfcf4be7952b8b8946cc626e > > Author: Tiago Pasqualini > > Date: Wed Sep 4 20:52:30 2024 -0300 > > > > crypto: run qcrypto_pbkdf2_count_iters in a new thread > > > > Unfortunately this has a subtle bug on machines which are very fast. > > > > On the first time around the loop, the 'iterations' value is quite > > small (1 << 15), and so will run quite fast. Testing has shown that > > some machines can complete this benchmarking task in as little as > > 7 milliseconds. > > > > Unfortunately the 'getrusage' data is not updated at the time of > > the 'getrusage' call, it is done asynchronously by the schedular. > > The 7 millisecond completion time for the benchmark is short > > enough that 'getrusage' sometimes reports 0 accumulated execution > > time. > > > > As a result the 'delay_ms == 0' sanity check in the above commit > > is triggering non-deterministically on such machines. > > > > The benchmarking loop intended to run multiple times, increasing > > the 'iterations' value until the benchmark ran for > 500 ms, but > > the sanity check doesn't allow this to happen. > > > > To fix it, we keep a loop counter and only run the sanity check > > after we've been around the loop more than 5 times. At that point > > the 'iterations' value is high enough that even with infrequent > > updates of 'getrusage' accounting data on fast machines, we should > > see a non-zero value. > > > > Reported-by: Thomas Huth > > Reported-by: Richard W.M. Jones > > Signed-off-by: Daniel P. Berrangé > > Is this a qemu-stable material (9.2)? Yes, please include it. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|