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From: Akira Tsukamoto <akira.tsukamoto@gmail.com>
To: Ben Dooks <ben.dooks@codethink.co.uk>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
Subject: Re: [PATCH v2 0/5] riscv: improving uaccess with logs from network bench
Date: Tue, 22 Jun 2021 21:05:27 +0900	[thread overview]
Message-ID: <f54ec904-2bf5-0c29-d467-7465993d5d6b@gmail.com> (raw)
In-Reply-To: <e7d5f98b-5e0d-19b3-08f5-a7b49d542a85@codethink.co.uk>

On 6/22/2021 5:30 PM, Ben Dooks wrote:
> On 19/06/2021 12:21, Akira Tsukamoto wrote:
>> Optimizing copy_to_user and copy_from_user.
>>
>> I rewrote the functions in v2, heavily influenced by Garry's memcpy
>> function [1].
>> The functions must be written in assembler to handle page faults manually
>> inside the function.
>>
>> With the changes, improves in the percentage usage and some performance
>> of network speed in UDP packets.
>> Only patching copy_user. Using the original memcpy.
>>
>> All results are from the same base kernel, same rootfs and same
>> BeagleV beta board.
>>
>> Comparison by "perf top -Ue task-clock" while running iperf3.
> 
> I did a quick test on a SiFive Unmatched with IO to an NVME.
> 
> before: cached-reads=172.47MB/sec, buffered-reads=135.8MB/sec
> with-patch: cached-read=s177.54Mb/sec, buffered-reads=137.79MB/sec
> 
> That was just one test run, so there was a small improvement. I am
> sort of surprised we didn't get more of a win from this.
> 
> perf record on hdparm shows that it spends approx 15% cpu time in
> asm_copy_to_user. Does anyone have a benchmark for this which just
> looks at copy/to user? if not should we create one?

Thanks for the result on the Unmatched with hdparm. Have you tried
iperf3?

The 15% is high, is it before or with-patch?

Akira

  reply	other threads:[~2021-06-22 12:05 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-19 11:21 Akira Tsukamoto
2021-06-19 11:34 ` [PATCH 1/5] riscv: __asm_to/copy_from_user: delete existing code Akira Tsukamoto
2021-06-21 11:45   ` David Laight
2021-06-21 13:55     ` Akira Tsukamoto
2021-06-19 11:35 ` [PATCH 2/5] riscv: __asm_to/copy_from_user: Adding byte copy first Akira Tsukamoto
2021-06-19 11:36 ` [PATCH 3/5] riscv: __asm_to/copy_from_user: Copy until dst is aligned Akira Tsukamoto
2021-06-19 11:37 ` [PATCH 4/5] riscv: __asm_to/copy_from_user: Bulk copy while shifting Akira Tsukamoto
2021-06-19 11:43 ` [PATCH 5/5] riscv: __asm_to/copy_from_user: Bulk copy when both src, dst are aligned Akira Tsukamoto
2021-06-21 11:55   ` David Laight
2021-06-21 14:13     ` Akira Tsukamoto
2021-06-20 10:02 ` [PATCH v2 0/5] riscv: improving uaccess with logs from network bench Ben Dooks
2021-06-20 16:36   ` Akira Tsukamoto
2021-06-22  8:30 ` Ben Dooks
2021-06-22 12:05   ` Akira Tsukamoto [this message]
2021-06-22 17:45     ` Ben Dooks
2021-07-12 21:24 ` Ben Dooks

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