From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: md-RAID5/6 stripe_cache_size default value vs performance vs memory footprint Date: Fri, 27 Dec 2013 09:14:07 +1100 Message-ID: <20131227091407.2ac401d1@notabene.brown> References: <52B102FF.8040404@pzystorm.de> <52B2FE9E.50307@hardwarefreak.com> <52B41B67.9030308@pzystorm.de> <201312202343.47895.arekm@maven.pl> <52B57912.5080000@hardwarefreak.com> <20131226085510.GB32660@infradead.org> <52BBF5B0.8020206@hardwarefreak.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============8430431263562188633==" Return-path: In-Reply-To: <52BBF5B0.8020206@hardwarefreak.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: stan@hardwarefreak.com Cc: Christoph Hellwig , linux-raid@vger.kernel.org, "xfs@oss.sgi.com" List-Id: linux-raid.ids --===============8430431263562188633== Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/tIziOH9cKrE+.8RfYN9tXTg"; protocol="application/pgp-signature" --Sig_/tIziOH9cKrE+.8RfYN9tXTg Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Thu, 26 Dec 2013 03:24:00 -0600 Stan Hoeppner wrote: > On 12/26/2013 2:55 AM, Christoph Hellwig wrote: > > On Sat, Dec 21, 2013 at 05:18:42AM -0600, Stan Hoeppner wrote: > >> The powers that be, Linus in particular, are not fond of default > >> settings that create a lot of kernel memory structures. The default > >> md-RAID5/6 stripe_cache-size yields 1MB consumed per member device. > >=20 > > The default sizing is stupid as it basically makes RAID unusable out > > of the box, I always have to fix that up, as well as a somewhat > > reasonable chunk size for parity RAID to make it usable. I'm also > > pretty sure I complained about it at least once a while ago, but never > > got a reply. >=20 > IIRC you Dave C. and myself all voiced criticism after the default chunk > size was changed from 64KB to 512KB. I guess we didn't make a strong > enough case to have it reduced, or maybe didn't use the right approach. >=20 > Maybe Neil is waiting for patches to be submitted for changing these > defaults, and to argue the merits in that context instead of pure > discussion? Dunno. Just guessing. Maybe he'll read this and jump in. >=20 Good guess. NeilBrown --Sig_/tIziOH9cKrE+.8RfYN9tXTg Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIVAwUBUryqLznsnt1WYoG5AQLoHg//UItjEDouIilQklR4madQsEbK3UCw7lII eIA+mci0diPdTpgZa1PAXaeAU4A0hf1GNUaMXsZRMzeSiR2pfW+UVKDGG02VkzNz QzchxXX6K5l1dNBQqcSGDtSKpcFuj9CJ0Z/GHdid/FzJVG9yJ3vYz9eLBk0UD6UA 4ehWxwhAjIA4pSmCJA81/T3n/cVPA53i8XWzXCCO5/sCZ9v6/pPxAt2TZKspbCZF o/S+x5O9g8h7QHbiwT2BkdJaJMGB+BzqUe4N5Ytd74JF/a388BQgi7Z2ZFb2ihhW USuMgt2JvRo50zYMiD9mnCSERAQWnNedUnWEnoj3y1cx0KeS1Fcce08MctQ578Q+ 5jl0NMoqyvWZ60rmjfWGPKnyPlxuDkFhPH5fKouuwk3L93WwbvQMBRhgiG3qSTv8 kM5NGSRgbu/V6fU5ZU0fydwqpJfgo1oV26eiztPD/IBcK3EltJ8wtgFO36CO5Pa1 iYG19K79Zj099e2WdCdbi6nnhKdE2fQNsXcgGRMaBgkMxHN8kccvb91YzQBbqdVA RDr5/8o9leukHuclL9EdRdwQoyEhgrbFTcbe5j+AcTv50MhNb5izCUeit63Plj73 xWw20eFaWq8DsEh0vvBA3SzuG+xeKWSBRtLiTNFQsAl6BuJFfVff4SdjirjQZRpm x+LSZDZlv0g= =NrrL -----END PGP SIGNATURE----- --Sig_/tIziOH9cKrE+.8RfYN9tXTg-- --===============8430431263562188633== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs --===============8430431263562188633==--