Messages in this thread | | | Subject | Re: [ANNOUNCE] util-linux-ng v2.17 (stable) | From | Artem Bityutskiy <> | Date | Mon, 11 Jan 2010 21:17:28 +0200 |
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On Mon, 2010-01-11 at 15:05 +0100, Pavel Machek wrote: > On Fri 2010-01-08 13:43:47, H. Peter Anvin wrote: > > On 01/08/2010 01:33 AM, Karel Zak wrote: > > > > > > fdisk: > > > - the fdisk command aligns newly created partitions to minimum_io_size > > > boundary ("minimum_io_size" is physical sector size or stripe chunk > > > size on RAIDs). > > > > > > - the fdisk command supports disks with alignment_offset now. > > > > > > > I think we should align, by default, much more aggressively than that -- > > because frequently we just don't know what the real physical alignment > > is (think of flash media, which uses large erase blocks underneath.) > > Flash has special mapping layer, and does not care (SD/MMC), or is a > raw nand and can't be used as block device (smartmedia).
MMC does care, and we measured it, non-4KiB aligned writes were noticeably slower on real eMMC and some MMC cards. I cannot remember the numbers, but I vaguely recall something like 11%.
So the first statement is incorrect. It really does matter. E.g., we observed that FAT FS was slower if the partition did not start from 4KiB boundary.
-- Best Regards, Artem Bityutskiy (Артём Битюцкий)
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