From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pz0-f43.google.com ([209.85.210.43]) by canuck.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1QkBA8-0001he-KY for linux-mtd@lists.infradead.org; Fri, 22 Jul 2011 08:32:49 +0000 Received: by pzk1 with SMTP id 1so3336742pzk.16 for ; Fri, 22 Jul 2011 01:32:45 -0700 (PDT) Subject: Re: Can major re-organization activities of the UBIfs be "deliberately provoked"? From: Artem Bityutskiy To: Atlant Schmidt Date: Fri, 22 Jul 2011 11:34:02 +0300 In-Reply-To: <0A40042D85E7C84DB443060EC44B3FD32A7208F97E@dekaexchange07.deka.local> References: <0A40042D85E7C84DB443060EC44B3FD32A7208F97E@dekaexchange07.deka.local> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Message-ID: <1311323646.20707.18.camel@sauron> Mime-Version: 1.0 Cc: "'linux-mtd@lists.infradead.org'" Reply-To: dedekind1@gmail.com List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2011-07-21 at 09:33 -0400, Atlant Schmidt wrote: > Folks: > > We're using the UBIfs with our realtime equipment. We've > noticed a behavior where, every so often, the flush-ubifs > thread demands very, very large amounts of CPU time, blocking > all of our other processes that use the Linux time-sliced > scheduler. These bursts come at arbitrary intervals but > commonly last ten to fifteen seconds. If the bursts are probably dues to write-back which is initiated by VFS. When UBIFS is doing write-back it needs to compress data, it may need to do GC if there is not space. First - check if the bursts are indeed about write-back - change the period of write-back and see. Or type sync and see the utilization. Then you can play with VFS knobs and lessen the write-back intervals in /proc. -- Best Regards, Artem Bityutskiy