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

[Mark Lord <kernel@teksavvy.com>]

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