From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Date: Mon, 14 May 2007 08:08:19 +0000 Subject: Re: [blktrace] unplug queue trace action is missed at some places Message-Id: <20070514080819.GE7572@kernel.dk> List-Id: References: <1178897976.3335.20.camel@dhcp0-54.sw.ru> In-Reply-To: <1178897976.3335.20.camel@dhcp0-54.sw.ru> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-btrace@vger.kernel.org On Mon, May 14 2007, Vasily Tarasov wrote: > On Mon, 2007-05-14 at 09:40 +0200, Jens Axboe wrote: > > On Fri, May 11 2007, Vasily Tarasov wrote: > > > Hello all, > > > > > > The function blk_start_queueing() calls __generic_unplug_device() > > > function directly without tracing BLK_TA_UNPLUG_IO action. So I have an > > > odd output of blktrace, when requests go through the plugged queue. I > > > suppose it's a BUG, or do I miss something? > > > > The unplug trace is meant to log upper layers doing an unplug to start > > IO, not internal use that wants to kick the queue for whatever reasons. > > We could log those as well, but it would be preferential to seperate > > them. > > > > blk_start_queuing() is one such call, for instance. > > > > Thank you, now I understand it. I believe it is very necessary to trace > internal unplugging (as a separate case), because such trace: > > 3,64 1 46 5.227907883 10539 P R [randreader] > 3,64 1 47 5.227908103 10539 I R 2068072 + 8 > [randreader] > 3,64 1 48 5.227909288 10539 D R 2068072 + 8 > [randreader] > 3,64 1 49 5.227931205 10539 Q R 2068088 + 112 > [randreader] > 3,64 1 50 5.227932222 10539 G R 2068088 + 112 > [randreader] > 3,64 1 51 5.227932827 10539 I R 2068088 + 112 > [randreader] > 3,64 1 52 5.227985593 10539 C R 2068072 + 8 [0] > > looks a bit confusing. I agree, it should definitely be added. I'll make sure it does! -- Jens Axboe