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 lists1p.gnu.org (lists1p.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 BDCD3C98302 for ; Wed, 23 Sep 2026 14:51:04 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x9OJD-0007XA-Lr; Wed, 23 Sep 2026 10:50:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x9OIj-0007Ef-N8 for qemu-devel@nongnu.org; Wed, 23 Sep 2026 10:50:33 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x9OIg-0001M6-G3 for qemu-devel@nongnu.org; Wed, 23 Sep 2026 10:50:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1790175011; 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: in-reply-to:in-reply-to:references:references; bh=1f97IEyRjAnLvn6hoLL6tqGRvTg2c/nkT5NL2mKTwvk=; b=aTYl1FRDt8DKAeyhKAJ1zJp3F8PQVgRvr7zNdB8GdC8QEbYME7G2EOVe92Oo8lHA8sw3Fk MTDdYb9H/k9pM40+mvVjwROR2Mi9vZN6UNrEh+XCTpE3sQcHUdv5V2CEaW4mUEBHa5KpIr uaqj6gj/8IJneCaZ9A1ZoqUh4sz4Q54= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-332-4IwIAShxMRet9A5fbOVHCg-1; Wed, 23 Sep 2026 10:50:07 -0400 X-MC-Unique: 4IwIAShxMRet9A5fbOVHCg-1 X-Mimecast-MFC-AGG-ID: 4IwIAShxMRet9A5fbOVHCg_1790175006 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3572B180ACCE; Wed, 23 Sep 2026 14:50:06 +0000 (UTC) Received: from redhat.com (unknown [10.44.48.191]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 840AF195604B; Wed, 23 Sep 2026 14:50:03 +0000 (UTC) Date: Wed, 23 Sep 2026 16:50:00 +0200 From: Kevin Wolf To: Hanna Czenczek Cc: Stefan Hajnoczi , qemu-block@nongnu.org, qemu-devel@nongnu.org, John Snow , "Denis V . Lunev" , Eric Blake , Markus Armbruster Subject: Re: [PATCH 0/9] block: BLOCK_IO_DELAY event Message-ID: References: <20260831135206.126184-1-hreitz@redhat.com> <20260903140815.GC825275@fedora> <8592119d-665d-482e-9502-8f4a1a69c10d@redhat.com> <20260921204126.GC115897@fedora> <6a6a77e9-8acb-4312-aa38-e06f81ac882e@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6a6a77e9-8acb-4312-aa38-e06f81ac882e@redhat.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Am 23.09.2026 um 12:48 hat Hanna Czenczek geschrieben: > > > > When an I/O request hangs for a long time, the management tool will be > > > > unable to detect that the threshold has been exceeded in a timely > > > > manner. > > > Yes. But why would that be a real problem? > > > > > > Given the request so far is only to notify users of their storage block > > > showing problematic latencies at all, there is no need to provide the alerts > > > in actual real time. > > What does the current approach solve that is not already possible with > > the block latency histogram? > > See what I linked above. Apparently having to repeatedly query the histogram > repeatedly is not deemed nice enough. It's the difference between an event and active polling. I would agree that active polling isn't the right answer in most cases. Kevin