Received: by 2002:a25:824b:0:0:0:0:0 with SMTP id d11csp6671089ybn; Mon, 30 Sep 2019 01:43:00 -0700 (PDT) X-Google-Smtp-Source: APXvYqxR+6IgHCk/YFq+LTRQnyYwosoaNxAb8NgGtFXPHlDGwXH0DGHwF09BpZMNcL4uW6mnSbwZ X-Received: by 2002:a50:cf8b:: with SMTP id h11mr17479867edk.236.1569832980371; Mon, 30 Sep 2019 01:43:00 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1569832980; cv=none; d=google.com; s=arc-20160816; b=UONPNmhpJQup9FD54aEfAESav+zdGhwMTzi4k884fYHwOKyW7wCLjKk61FaUvBGk/f MG0GGzU4p4u6LsxlNPSW6fsGzxp8hHH8N0IoF10NF5Ni/QbCpMuCA47+BmXIvbtOUkQ0 XAoX+HCqG2lZZgvflF4uhD2WHXdNIfXw5PXfQrc2xmpBCvOuFz/bdWSNLONBq4/uqekF 4s2TzlWwYtvwWhhkIP4RNeCjSOdvKfT9Jpvvos2BvKW5rTIn0LA9mfgzL9c/RGa9TYyQ 7D5PMFPBkGVd1lUHO4wZa/ScX4DaUT0Ol2MkX6dtwrGKk80ZLS4uebliFPxOcw+L7q8T Jr0w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:date:cc:to:from:subject :message-id; bh=ErjNRkgludfXdUS0CrBDYmm4EaOaxXAo99JwCwytdSU=; b=I2dxqiX9d5UQI8RyVE9iiEgay26r/W8UTV88h9HS54ukYkJbTbwRdLPT+pE7YbCUu0 LpWh/0Es1apuW6uPbbqCk+YbFd6DHMGPlCgWiZfyRgH7AYg2sJtOGzpHa9Qpf+8/UaWm HqK7/WLpxawGkdoDXm7Y3X4Ud0EAODBhIGVygKE0k2PJJBCVXzrnKYoLaSRqh+LNEGTu kX7mabAO0PwNpqVZGVWIl4H6l2eKkj9031M5BZoAsWOjXBizh1flyPprC3jYG3Y/BCvP wCpg0dcuh6kNfBqNjvgzxoY2A+J7Eaj7OZpW8jYHOk1xtfnG1rALB3Cj3x3tG9L5WQeY CZeQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id n8si6422391ejh.169.2019.09.30.01.42.34; Mon, 30 Sep 2019 01:43:00 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729996AbfI3ImK (ORCPT + 99 others); Mon, 30 Sep 2019 04:42:10 -0400 Received: from mx2.suse.de ([195.135.220.15]:48202 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726121AbfI3ImK (ORCPT ); Mon, 30 Sep 2019 04:42:10 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id ECC0AAFD4; Mon, 30 Sep 2019 08:42:08 +0000 (UTC) Message-ID: Subject: Re: [PATCH] scsi: core: Log SCSI command age with errors From: Martin Wilck To: Laurence Oberman , "Milan P. Gandhi" , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Cc: jejb@linux.ibm.com, martin.petersen@oracle.com Date: Mon, 30 Sep 2019 10:42:14 +0200 In-Reply-To: <3a8ee584f9846fba94d98d0e6941fefdcbed5d71.camel@redhat.com> References: <20190923060122.GA9603@machine1> <471732f03049a1528df1d144013d723041f0a419.camel@suse.de> <3a8ee584f9846fba94d98d0e6941fefdcbed5d71.camel@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.32.4 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2019-09-27 at 13:45 -0400, Laurence Oberman wrote: > > Hi Martin > > Agreed about log extraction, but turning that on with a busy workload > in a production environment is not practical. We cant do it with > systems with 1000's of luns and 1000's of IOPS/sec. > Also second resolution is good enough for the debug we want to see. I gather that you look at a specific problem where second resolution is sufficient. For upstream, the generic usefulness should be considered, and I don't think we can say today that better-than-second resolution will never be useful, so I still vote for milliseconds. Wrt the enablement of the option on highly loaded systems, I'm not sure I understand. You need to enable SCSI logging anyway, don't you? Is it an issue to have to set 2 sysfs values rather than just one? Regards, Martin > > Regards > Laurence >