Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super_operation

Christoph Hellwig
2010-12-07T09:28:00Z

On Fri, Nov 19, 2010 at 10:21:35AM -0500, Mark Lord wrote:
> >I really hate to rely on this third party hearsay (from all sides), and
> >have implement TRIM support in qemu now. I'll soon install win7 and
> >will check out the TRIM patters myself.
>
> Excellent!

I did a Windows 7 installation under qemu today, and the result is:

- it TRIMs the whole device early during the installation
- after that I see a constant stream of small trims during the
installation. It's using lots of non-contiguous ranges in a single
TRIM command, with sizes down to 8 sectors (4k) for a single range.
- after installation there's is some background-trimming going on
even when doing no user interaction with the VM at all.
- removing files leads to an instant stream of TRIMs, again vectored
and of all sizes down to 4k. Note that the TRIMs are a lot more
instant than even with btrfs and -o discard, which delays most
TRIMs until doing a sync.