From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gordan Bobic Subject: Re: SSD and non-SSD Suitability Date: Sat, 29 May 2010 09:45:39 +0100 Message-ID: <4C00D433.2010406@bobich.net> References: <4BFCF55A.80205@bobich.net> <87typspmiq.wl%jir@sekiba.com> <4BFF91E7.9000102@bobich.net> <87d3wf17vj.wl%jir@sekiba.com> <4C00C745.6050903@prnet.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4C00C745.6050903-/LHdS3kC8BfYtjvyW6yDsg@public.gmane.org> Sender: linux-nilfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: David Arendt Cc: Jiro SEKIBA , linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org David Arendt wrote: >>>>> 4) As the data gets expired, and snapshots get deleted, this will >>>>> inevitably lead to fragmentation, which will de-linearize writes as they >>>>> have to go into whatever holes are available in the data. How does this >>>>> affect nilfs write performance? >>>>> >>>> For now, my understanding, nilfs garbage collector moves the live (in use) >>>> blocks to the end of logs, so holes are not created (it is correct?). >>>> However, it leads another issue that garbage collector process, which is >>>> nilfs_cleanerd, will consume the I/O. This is major I/O performance >>>> bottle neck current implementation. >>>> >>> Since this moves files, it sounds like this could be a major issue for >>> flash media since it unnecessarily creates additional writes. Can this >>> be suppressed? >>> >> You can simply kill the nilfs_clearnerd after you mount the nilfs partition. >> > If you use the latest nilfs_utils, killing nilfs_cleanerd is no longer > necessary. You can use mount -o nogc. This will not start > nilfs_cleanerd. Another possibility is to let nilfs_cleanerd start and > tweak min_free_segments and max_free_segments so that cleanerd will only > do cleaning if necessary. What about making the gc run only if the disk has been idle for, say, 20ms, unless min_free_segments is reached? Gordan -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html