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Message-ID: <CAMz4kuKOe8dT_K-8KQC_jMciCw-3jA_rxY22KG6347ENR-uGyQ@mail.gmail.com>
Date: Fri, 13 Nov 2015 19:37:21 +0800
From: Baolin Wang <baolin.wang@...aro.org>
To: Arnd Bergmann <arnd@...db.de>
Cc: Jan Kara <jack@...e.cz>, Christoph Hellwig <hch@...radead.org>,
Jens Axboe <axboe@...nel.dk>,
Alasdair G Kergon <agk@...hat.com>,
Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
neilb@...e.com, tj@...nel.org, jmoyer@...hat.com,
keith.busch@...el.com, bart.vanassche@...disk.com,
linux-raid@...r.kernel.org, Mark Brown <broonie@...nel.org>,
"Garg, Dinesh" <dineshg@...cinc.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/2] Introduce the request handling for dm-crypt
On 13 November 2015 at 17:05, Arnd Bergmann <arnd@...db.de> wrote:
> On Friday 13 November 2015 10:05:28 Baolin Wang wrote:
>>
>> Well, I did a simple test with dd reading, cause my engine limitation is 1M,
>> (1) so the time like below when handle 1M at one time.
>> 1048576 bytes (1.0 MB) copied, 0.0841235 s, 12.5 MB/s
>> 1048576 bytes (1.0 MB) copied, 0.0836294 s, 12.5 MB/s
>> 1048576 bytes (1.0 MB) copied, 0.0836526 s, 12.5 MB/s
>>
>> (2) These handle 64K at one time * 16 times
>> 1048576 bytes (1.0 MB) copied, 0.0937223 s, 11.2 MB/s
>> 1048576 bytes (1.0 MB) copied, 0.097205 s, 10.8 MB/s
>> 1048576 bytes (1.0 MB) copied, 0.0935884 s, 11.2 MB/s
>>
>> Here is a 10ms level difference, try to image if the hardware engine's
>> throughput is bigger than that. But like Jens said, we can measure it
>> by the performance data.
>
> The absolute numbers look really low. Does this include writing to
> a hard drive? That would certainly make the difference appear
> less significant.
>
OK, I'll supply the complete performance data to measure it.
> Could you try backing this with a ram disk backing for comparison,
> and also use 'time dd' to show the CPU utilization for all cases?
> For completeness, including cpu-only performance might also help
> put this into perspective.
>
OK, I'll try. Thanks.
> Arnd
--
Baolin.wang
Best Regards
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