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Date: Wed, 09 Nov 2011 21:58:18 +0100
From: Milan Broz <mbroz@redhat.com>
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References: <4EBAC310.6010104@alexanderkoch.net> <4EBACC60.4010907@redhat.com>
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Subject: Re: [dm-crypt] Testing TRIM with hdparm on dm-crypt
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To: Alexander Koch <mail@alexanderkoch.net>
Cc: dm-crypt@saout.de

On 11/09/2011 09:25 PM, Alexander Koch wrote:
>> You should be also able to trace discard (and other) block requests
>> using blktrace/btrace, this should be really more user friendly :)
> 
> I tried blktrace but didn't know which event to track. Supported list 
> includes READ, WRITE, BARRIER, SYNC, QUEUE, REQUEUE, ISSUE, COMPLETE, FS 
> and PC.

man blkparse and search for "discard", it should be marked 'D'

something like here, here using simulated scsi_debug device

# modprobe scsi_debug dev_size_mb=16 sector_size=512 num_tgts=1 lbpu=1

# btrace /dev/<scsi_debug device> -a issue
...
  8,144  1       19     0.002461433  2146  D   D 0 + 32768 [mkfs.ext4]

# fstrim <mountpoint>
...
  8,144  1       52     8.372211281  2239  D   D 162 + 2 [fstrim]
  8,144  1       53     8.382095450  2239  D   D 168 + 28 [fstrim]
  8,144  1       54     8.391463509  2239  D   D 1222 + 15164 [fstrim]
  8,144  1       55     8.402445119  2239  D   D 18564 + 14204 [fstrim]

Milan