From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.grid-net.com ([97.65.115.2]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1SNmHK-0000oM-3a for linux-mtd@lists.infradead.org; Fri, 27 Apr 2012 14:36:10 +0000 Message-ID: <4F9AAED7.2000800@grid-net.com> Date: Fri, 27 Apr 2012 07:36:07 -0700 From: Subodh Nijsure MIME-Version: 1.0 To: Artem Bityutskiy Subject: Re: Suggestion needed to set proper journal size References: <4F91EA56.50803@grid-net.com> <1335535527.1910.6.camel@koala> In-Reply-To: <1335535527.1910.6.camel@koala> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Cc: mtd List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 04/27/2012 07:05 AM, Artem Bityutskiy wrote: > On Fri, 2012-04-20 at 15:59 -0700, Subodh Nijsure wrote: >> Hello, >> >> I know general implications of changing journal size on UBIFS -- bigger >> the journal, >> longer it may take to replay the journal, increasing time UBIFS takes to >> mount. Smaller >> journal means more re-writes to flash. >> >> We created 2 partitions 100MB and 45MB and we see that by default >> mkfs.ubifs is reserving 8MB for journal. >> >> UBIFS: file system size: 101834752 bytes (99448 KiB, 97 MiB, 802 LEBs) >> UBIFS: journal size: 9023488 bytes (8812 KiB, 8 MiB, 72 LEBs) >> >> UBIFS: file system size: 47996928 bytes (46872 KiB, 45 MiB, 378 LEBs) >> UBIFS: journal size: 9023488 bytes (8812 KiB, 8 MiB, 72 LEBs) >> >> I know I can specify size of journal with -j option. >> >> Should the journal size be scaled in some proportion of size of UBIFS >> partition? > It does grow, but not infinitely. We have some heuristics in mkfs.ubifs, > but those were mostly taken out of thin air. I do not remember us doing > a lot of experimenting with that. > >> Should the journal size depend on how often you expect file-system to be >> updated? >> >> Has anyone done experiments with setting really small (1MB/2MB) journal >> size? >> What side effects is one likely to encounter if the journal size is too >> small. >> >> fwiw in my use case, file-system doesn't get updated that often, perhaps >> 2K data in about 4 files once a week. > I think you should do your own experiments. If you share the results - > will be nice. Yes, its on my to-do list once I am done resubmitting XATTR and integck patches. -Subodh