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Date: Mon, 13 Aug 2012 14:40:53 -0400 From: Theodore Ts'o <tytso@....edu> To: Zach Brown <zab@...hat.com> Cc: Andreas Dilger <adilger@...ger.ca>, Zheng Liu <wenqing.lz@...bao.com>, Eric Sandeen <sandeen@...hat.com>, Zheng Liu <gnehzuil.liu@...il.com>, ext4 development <linux-ext4@...r.kernel.org> Subject: Re: [PATCH v2] ext4: dynamical adjust the length of zero-out chunk On Mon, Aug 13, 2012 at 10:32:24AM -0700, Zach Brown wrote: > > we allow it to be tunable via sysfs and set an initial default value > > of 32, so instead of creating uninitalized extents smaller than > > s/32/16/? Oops, nice catch. > It'd be nice to define the tunable in terms of some fixed unit, kb or > mb, whatever, and then translate to the block size in the code so people > don't have to do that math by hand. > > No? Agreed, thanks for the suggestion. The next question is whether the default maximum zero-out size should be 256k (as previously documented) or 128k (as previously coded). The previously rule of thumb which I had used was that after doing a random seek, the time needed to write 4k and 32k was pretty much in the noise. But that was a number from several years ago. I suppose I should do some quick experiments to see what is a good number these days.... - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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