On Sat, 16 Aug 2008 18:38:41 +0100
David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
> On Sat, 2008-08-16 at 19:08 +0200, Pierre Ossman wrote:
> > I've cooked up some patches that maps David's new discard requests to
> > erase operations on MMC and SD cards. I'm not entirely sure these are
> > something to keep though as I've been unable to see any performance
> > increase in keeping blocks erased. Do we have any other reason to keep
> > it?
>
> When you fill a file system completely, then delete all files -- then do
> you see a performance improvement when you subsequently write to it?
>
When testing the new version, I've first erased the entire device using
the new ioctl. So the tests start with a completely erased device.
Basically the following:
./discard /dev/mmcblk0 0 `cat /sys/block/mmcblk0/size`
mkfs -t vfat /dev/mmcblk0
mount /dev/mmcblk0 /media/tmp
bonnie++ -d /media/tmp
The comparison is against a driver without erase support and a card
prepared by filling it with /dev/zero.
It might be that my testing methodology is flawed, so suggestions are
welcome (and people testing on their own for that matter).
--
-- Pierre Ossman
Linux kernel, MMC maintainer http://www.kernel.org
rdesktop, core developer http://www.rdesktop.org
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