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

From: Mark Lord
Date: Fri Nov 19 2010 - 10:30:44 EST


On 10-11-19 09:57 AM, Christoph Hellwig wrote:
On Fri, Nov 19, 2010 at 09:53:52AM -0500, Mark Lord wrote:
On 10-11-19 09:40 AM, Chris Mason wrote:

We've been told that online and constant trimming is the default in
windows7. The ssds are most likely to just start ignoring the trims
they can't service efficiently.

Win7 collects multiple TRIM ranges over time and batches them as single TRIMs
(as reported to me by an SSD vendor who traced it with a SATA analyzer,
and who also apparently has "inside info").

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.

Here is some of the heresay about Win7:

TRIM commands are sent when:
-- About 2/3 of partition is filled up, when file is (really) deleted,
not when merely sending file to trash bin.
-- In the above case, when trash bin gets emptied.
-- In the above case, when partition is deleted.

So the behaviour may vary, depending upon how full the filesystem is
at any point in time.

Cheers
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