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<p>+ Alasdair and dm-devel for awareness and inputs.<br>
</p>
<br>
<div class="moz-cite-prefix">On 5/9/2017 12:26 PM, Neeraj Soni
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:a66b6e17-a8c4-3465-fc2e-c3114abe0ca7@codeaurora.org">Hi
Keith/Snitzer,
<br>
<br>
I have recently started using kernel 4.4 on a Android device and
ran Androbench to check storage read/write performance. I found
that the Random Read (RR) and Random write(RW) performance with
Full Disk Encryption is degraded compared to no Disk Encryption.
Initially i thought this must the issue with the storage part used
and i compared the performance of similar storage part on a device
that was using Android with kernel 3.18. I found that with no Disk
Encryption the performance was equivalent to the device which was
using 4.4 but with Disk Encryption there was degradation in RR
(~20%) and RW(10%).
<br>
<br>
I then tried to compare the changes that was brought in kernel 4.4
in Full Disk Encryption path. I came across the patch mentioned in
subject and found that now a worker thread is scheduled in
dm_request_fn() to process the requests instead of directly
invoking map_request() as was in kernel 3.18.
<br>
<br>
I reverted this patch and found that the RR and RW performance was
now closer to what we have without Disk Encryption. From the
commit message i understand that this change is significant and
will be required for blk-mq support but have you came across such
degradation issue with your patch and do we have any fix for this
degradation available?
<br>
<br>
BR,
<br>
Neeraj Soni,</blockquote>
<blockquote type="cite"
cite="mid:a66b6e17-a8c4-3465-fc2e-c3114abe0ca7@codeaurora.org">--<br>
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