From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mitch Harder Subject: Re: [PATCH] btrfs file write debugging patch Date: Tue, 1 Mar 2011 08:51:45 -0600 Message-ID: References: <1298857223-sup-5612@think> <201102281114.00018.johannes.hirte@fem.tu-ilmenau.de> <20110228161056.GA2769@localhost.localdomain> <1298911556.11118.8.camel@mainframe> <1865303E0DED764181A9D882DEF65FB68662A5EA63@shsmsx502.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: =?ISO-8859-1?Q?Maria_Wikstr=F6m?= , Josef Bacik , Johannes Hirte , Chris Mason , "linux-btrfs@vger.kernel.org" To: "Zhong, Xin" Return-path: In-Reply-To: <1865303E0DED764181A9D882DEF65FB68662A5EA63@shsmsx502.ccr.corp.intel.com> List-ID: On Tue, Mar 1, 2011 at 4:14 AM, Zhong, Xin wrote: > Is your system running out of memory or is there any other thread like flush-btrfs competing for the same page? > There's no sign of memory pressure. Although I only have 1 GB in this box, I'm still show ~1/2 GB RAM free during this build. There's no swap space allocated, and nothing in dmesg that indicates there's a transient spike of RAM pressure. > I can only see one process in your ftrace log. You may need to trace all btrfs.ko function calls instead of a single process. Thanks! > That ftrace.log was run with ftrace defaults for a function trace. It should collect calls from the whole system. For the sake of consistency, I am intentionally trying to insure that very few other things are going on at the same time as this build. And I'm building with "-j1" so things will happen the same way each time. Also, I supplied just the tail end of the trace log. The full log shows a few of the other build processes leading up to the problem, but the ftrace ring buffer fills up surprisingly fast. Even with a 50MB ring buffer for ftrace, I usually collect less than 1 second of information when something busy like a build is going on. Let me know if you'd like to see the full log. It's bigger, but I can find someplace to put it. But I'm pretty sure that wmldbcreate is the only thing that is going on when the breakage occurs. Otherwise I wouldn't get such consistent breakage in the same spot every time.