On Sun, Jan 3, 2021 at 1:41 PM Matthew Miller <mattdm(a)fedoraproject.org> wrote:
On Sun, Jan 03, 2021 at 08:46:33PM +0100, Alessio wrote:
> What about that story related to the drop in the Btrfs performances in
> Kernel 5.10? Is it still true? Can we perform some specific test?
Looks like a fix is on the way:
https://marc.info/?l=linux-btrfs&m=160883350502962&w=2
It would be interesting to see if the performance regression is caught with
`sudo ./runtests.sh -t performance` as part of the standard test day tests.
I haven't experienced it day to day. But I can reproduce it as
originally described. I'm not seeing kernel-test suite pick up on
anything file system specific, but I do see quite a weird result for
16p/64K context switching. It's ~3 for 5.9 and ~83 for 5.10.
Processor, Processes - times in microseconds - smaller is better
------------------------------------------------------------------------------
Host OS Mhz null null open slct sig sig fork exec sh
call I/O stat clos TCP inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
fmac.loca Linux 5.9.16- 3396 0.05 0.11 0.91 1.66 2.45 0.11 0.72 794. 2338 3244
fmac.loca Linux 5.10.4- 3396 0.06 0.10 0.84 1.66 2.77 0.12 0.73 838. 2312 3298
Context switching - times in microseconds - smaller is better
-------------------------------------------------------------------------
Host OS 2p/0K 2p/16K 2p/64K 8p/16K 8p/64K 16p/16K 16p/64K
ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw
--------- ------------- ------ ------ ------ ------ ------ ------- -------
fmac.loca Linux 5.9.16- 3.2700 2.3000 4.0800 2.8600 2.8400 3.04000 3.28000
fmac.loca Linux 5.10.4- 3.2800 3.5900 5.3500 2.8400 3.1500 3.03000 83.0
*Local* Communication latencies in microseconds - smaller is better
---------------------------------------------------------------------
Host OS 2p/0K Pipe AF UDP RPC/ TCP RPC/ TCP
ctxsw UNIX UDP TCP conn
--------- ------------- ----- ----- ---- ----- ----- ----- ----- ----
fmac.loca Linux 5.9.16- 3.270 5.154 14.1 25.5 25.8 40.
fmac.loca Linux 5.10.4- 3.280 6.072 13.0 25.7 23.5 44.
File & VM system latencies in microseconds - smaller is better
-------------------------------------------------------------------------------
Host OS 0K File 10K File Mmap Prot Page 100fd
Create Delete Create Delete Latency Fault Fault selct
--------- ------------- ------ ------ ------ ------ ------- ----- ------- -----
fmac.loca Linux 5.9.16- 16.4 16.3 25.2 20.0 1751.3K 0.357 0.00260 1.124
fmac.loca Linux 5.10.4- 16.8 16.7 26.1 20.0 1726.9K 0.335 0.00260 1.184
*Local* Communication bandwidths in MB/s - bigger is better
-----------------------------------------------------------------------------
Host OS Pipe AF TCP File Mmap Bcopy Bcopy Mem Mem
UNIX reread reread (libc) (hand) read write
--------- ------------- ---- ---- ---- ------ ------ ------ ------ ---- -----
fmac.loca Linux 5.9.16- 4150 9401 4573 6874.8 10.7K 6556.7 4081.1 9265 6472.
fmac.loca Linux 5.10.4- 4045 9500 4534 6597.2 10.3K 5523.1 4034.5 9107 6076.
[chris@fmac kernel-tests]$
--
Chris Murphy