From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lpp01m010-f49.google.com ([209.85.215.49]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1SNlnj-0002pD-1R for linux-mtd@lists.infradead.org; Fri, 27 Apr 2012 14:05:36 +0000 Received: by lagy4 with SMTP id y4so606742lag.36 for ; Fri, 27 Apr 2012 07:05:30 -0700 (PDT) Message-ID: <1335535527.1910.6.camel@koala> Subject: Re: Suggestion needed to set proper journal size From: Artem Bityutskiy To: Subodh Nijsure Date: Fri, 27 Apr 2012 17:05:27 +0300 In-Reply-To: <4F91EA56.50803@grid-net.com> References: <4F91EA56.50803@grid-net.com> Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-pBaw8FImvxAJn0nH2Q1p" Mime-Version: 1.0 Cc: mtd List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-pBaw8FImvxAJn0nH2Q1p Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2012-04-20 at 15:59 -0700, Subodh Nijsure wrote: > Hello, >=20 > I know general implications of changing journal size on UBIFS -- bigger= =20 > the journal, > longer it may take to replay the journal, increasing time UBIFS takes to= =20 > mount. Smaller > journal means more re-writes to flash. >=20 > We created 2 partitions 100MB and 45MB and we see that by default=20 > mkfs.ubifs is reserving 8MB for journal. >=20 > UBIFS: file system size: 101834752 bytes (99448 KiB, 97 MiB, 802 LEBs) > UBIFS: journal size: 9023488 bytes (8812 KiB, 8 MiB, 72 LEBs) >=20 > UBIFS: file system size: 47996928 bytes (46872 KiB, 45 MiB, 378 LEBs) > UBIFS: journal size: 9023488 bytes (8812 KiB, 8 MiB, 72 LEBs) >=20 > I know I can specify size of journal with -j option. >=20 > Should the journal size be scaled in some proportion of size of UBIFS=20 > 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= =20 > updated? >=20 > Has anyone done experiments with setting really small (1MB/2MB) journal= =20 > size? > What side effects is one likely to encounter if the journal size is too= =20 > small. >=20 > fwiw in my use case, file-system doesn't get updated that often, perhaps= =20 > 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. --=20 Best Regards, Artem Bityutskiy --=-pBaw8FImvxAJn0nH2Q1p Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAABAgAGBQJPmqenAAoJECmIfjd9wqK0Cg4QANKIkX7DVwCdWkD3tB2r69XA DHmES6MhbmMLSRx6LuqLwZnFSdT8u0JrGlJGbSS8ZaNdCje8oalA8m3uIglFkyo3 s3SOrlCehS43mPkGIszUMfbZmpKbx2AHka/IZruDNgnPg+KHKHAowr8wlGFmAL/9 5Dutk3Rwad7M2a3mRBb5dlbL7RWeyPqTvE6wCSZUUnCvFCO9FGNxzMdV5Fxc8ElW O1pWsyaDFyykttwFOGzelXEgmQXu9JBcmD7OR02Pw+oz2wXhDJYkHib2J6Xlkg1n gYrIwllh1JBhK1+4B1CuUUfKztKKhOYk/yo1w6YP+6pUPMeETkG3D1wJQkrIHBsH SIIvifPW7YqED8oPKLMjtsc/qyhMrBcGuPByIc0xMlOxwuGotOdPPjtUdY9WDoVT RAxXW3i8EyAatfICNN3GKt75/TvDyNXUyTt5CZi/JFXtb5Q3nvqXLBMlMbnYUtiy AKD5lsK3MN/CV86N+N6QX14wYJBs1Y2fb4rfpNeranifscqUSv4/LLOgNhU3J7ah D5GNqmdAqrvihTYYENiqsYW/w3pTD6ephiX4Ys7H8VoggDR11QHI0O7uOO1cFOTn fSuMSneUrLwCIcr8pFKAJEBXixJ7drCfcBOiRs2DP/IQbBNh8AS+qdiSCvYschyY BIlAoeJSjTY/+wLlGxqK =WIHa -----END PGP SIGNATURE----- --=-pBaw8FImvxAJn0nH2Q1p--