From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hubert Kario Subject: Re: ssd option for USB flash drive? Date: Thu, 19 May 2011 21:53:24 +0200 Message-ID: <201105192153.24797.hka@qbs.com.pl> References: <20110517220252.GA12323@yahoo.fr> <201105192104.58726.hka@qbs.com.pl> Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Cc: "linux-btrfs" To: Stephane Chazelas Return-path: In-Reply-To: <201105192104.58726.hka@qbs.com.pl> List-ID: Sorry, loks like list mailer doesn't like SMIME messages. On Thursday 19 of May 2011 21:04:54 Hubert Kario wrote: > On Wednesday 18 of May 2011 00:02:52 Stephane Chazelas wrote: > > Hiya, > >=20 > > I've not found much detail on what the "ssd" btrfs mount option > > did. Would it make sense to enable it to a fs on a USB flash > > drive? >=20 > yes, enabling discard is pointless though (no USB storage supports it > AFAIK). >=20 > > I'm using btrfs (over LVM) on a Live Linux USB stick to benefit > > from btrfs's compression and am trying to improve the > > performance. >=20 > ssd mode won't improve performance by much (if any). >=20 > You need to remember that USB2.0 is limited to about 20-30MiB/s (depe= nding > on CPU) so it will be slow no matter what you do >=20 > > Would anybody have any recommendation on how to improve > > performance there? Like what would be the best way to > > enable/increase writeback buffer or any way to make sure writes > > are delayed and asynchronous? Would disabling read-ahead help? > > (at which level would it be done?). Any other tip (like > > disabling atime, aligning blocks/extents, figure out erase block > > sizes if relevant...)? >=20 > aligning logical blocks to erase blocks can give some performance but= the > only way to make it really fast is not to use USB >=20 > > Many thanks in advance, > > Stephane --=20 Hubert Kario QBS - Quality Business Software 02-656 Warszawa, ul. Ksawer=F3w 30/85 tel. +48 (22) 646-61-51, 646-74-24 www.qbs.com.pl -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html