Messages in this thread | | | Subject | Re: [PATCH v2 0/5] riscv: improving uaccess with logs from network bench | From | Akira Tsukamoto <> | Date | Tue, 22 Jun 2021 21:05:27 +0900 |
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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
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