From: Ben Dooks <ben.dooks@codethink.co.uk>
To: Akira Tsukamoto <akira.tsukamoto@gmail.com>,
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 09:30:26 +0100 [thread overview]
Message-ID: <e7d5f98b-5e0d-19b3-08f5-a7b49d542a85@codethink.co.uk> (raw)
In-Reply-To: <5a5c07ac-8c11-79d3-46a3-a255d4148f76@gmail.com>
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?
--
Ben Dooks http://www.codethink.co.uk/
Senior Engineer Codethink - Providing Genius
https://www.codethink.co.uk/privacy.html
WARNING: multiple messages have this Message-ID (diff)
From: Ben Dooks <ben.dooks@codethink.co.uk>
To: Akira Tsukamoto <akira.tsukamoto@gmail.com>,
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 09:30:26 +0100 [thread overview]
Message-ID: <e7d5f98b-5e0d-19b3-08f5-a7b49d542a85@codethink.co.uk> (raw)
In-Reply-To: <5a5c07ac-8c11-79d3-46a3-a255d4148f76@gmail.com>
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?
--
Ben Dooks http://www.codethink.co.uk/
Senior Engineer Codethink - Providing Genius
https://www.codethink.co.uk/privacy.html
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next prev parent reply other threads:[~2021-06-22 8:30 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-19 11:21 [PATCH v2 0/5] riscv: improving uaccess with logs from network bench Akira Tsukamoto
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
2021-06-19 11:34 ` Akira Tsukamoto
2021-06-21 11:45 ` David Laight
2021-06-21 11:45 ` David Laight
2021-06-21 13:55 ` Akira Tsukamoto
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 11:35 ` 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 11:36 ` 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 11:37 ` 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
2021-06-19 11:43 ` Akira Tsukamoto
2021-06-21 11:55 ` David Laight
2021-06-21 11:55 ` David Laight
2021-06-21 14:13 ` Akira Tsukamoto
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 10:02 ` Ben Dooks
2021-06-20 16:36 ` Akira Tsukamoto
2021-06-20 16:36 ` Akira Tsukamoto
2021-06-22 8:30 ` Ben Dooks [this message]
2021-06-22 8:30 ` Ben Dooks
2021-06-22 12:05 ` Akira Tsukamoto
2021-06-22 12:05 ` Akira Tsukamoto
2021-06-22 17:45 ` Ben Dooks
2021-06-22 17:45 ` Ben Dooks
2021-07-12 21:24 ` Ben Dooks
2021-07-12 21:24 ` Ben Dooks
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