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[104.188.17.28]) by smtp.gmail.com with ESMTPSA id i16sm12546753pfa.184.2019.10.28.22.46.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Oct 2019 22:46:23 -0700 (PDT) Date: Mon, 28 Oct 2019 22:46:20 -0700 From: Bjorn Andersson To: cang@codeaurora.org Cc: Avri Altman , "Winkler, Tomas" , asutoshd@codeaurora.org, nguyenb@codeaurora.org, rnayak@codeaurora.org, linux-scsi@vger.kernel.org, kernel-team@android.com, saravanak@google.com, salyzyn@google.com, Alim Akhtar , Pedro Sousa , "James E.J. Bottomley" , "Martin K. Petersen" , Evan Green , Janek Kotas , Stanley Chu , Bean Huo , Subhash Jadavani , Arnd Bergmann , open list Subject: Re: [PATCH v1 1/1] scsi: ufs: Add command logging infrastructure Message-ID: <20191029054620.GG1929@tuxbook-pro> References: <1571808560-3965-1-git-send-email-cang@codeaurora.org> <5B8DA87D05A7694D9FA63FD143655C1B9DCF0AFE@hasmsx108.ger.corp.intel.com> <01eb3c55e35738f2853fbc7175a12eaa@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01eb3c55e35738f2853fbc7175a12eaa@codeaurora.org> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 28 Oct 19:37 PDT 2019, cang@codeaurora.org wrote: > On 2019-10-23 18:33, Avri Altman wrote: > > > > > > > Add the necessary infrastructure to keep timestamp history of > > > > commands, events and other useful info for debugging complex issues. > > > > This helps in diagnosing events leading upto failure. > > > > > > Why not use tracepoints, for that? > > Ack on Tomas's comment. > > Are there any pieces of information that you need not provided by the > > upiu tracer? > > > > Thanks, > > Avri > > In extreme cases, when the UFS runs into bad state, system may crash. There > may not be a chance to collect trace. If trace is not collected and failure > is hard to be reproduced, some command logs prints would be very helpful to > help understand what was going on before we run into failure. > This is a common problem shared among many/all subsystems, so it's better to rely on a generic solution for this; such as using tracepoints dumped into pstore/ramoops. Regards, Bjorn