Re: Low TCP throughput due to vmpressure with swap enabled

Yu Zhao
2022-11-24T01:18:54Z

On Wed, Nov 23, 2022 at 2:22 PM Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> On Tue, Nov 22, 2022 at 05:44:44PM -0700, Yu Zhao wrote:
> > Hi Johannes,
> >
> > Do you think it makes sense to have the below for both the baseline and
> > MGLRU or it's some behavior change that the baseline doesn't want to
> > risk?
>
> It looks good to me. Besides the new FMODE_NOREUSE, it's also a nice
> cleanup on the rmap side!
>
> It would just be good to keep the comment from folio_referenced_one() and
> move it to the vma_has_locality() check in invalid_folio_referenced_vma().
>
> Otherwise,
>
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Thanks.

I've added Ivan's test case to my collection. Interestingly, after
this patch, the download speed increased while fio was running (my
guess is that fio pushed more cold anon into swap):

$ uname
Linux test127 6.1.0-rc6-dirty #2 SMP PREEMPT_DYNAMIC Wed Nov 23
16:51:20 MST 2022 x86_64 x86_64 x86_64 GNU/Linux

$ go version
go version go1.18.1 linux/amd64

$ fio -v
fio-3.28

$ curl --version
curl 7.81.0 (x86_64-pc-linux-gnu) libcurl/7.81.0 OpenSSL/3.0.2
zlib/1.2.11 brotli/1.0.9 zstd/1.4.8 libidn2/2.3.2 libpsl/0.21.0
(+libidn2/2.3.2) libssh/0.9.6/openssl/zlib nghttp2/1.43.0 librtmp/2.3
OpenLDAP/2.5.13
Release-Date: 2022-01-05
Protocols: dict file ftp ftps gopher gophers http https imap imaps
ldap ldaps mqtt pop3 pop3s rtmp rtsp scp sftp smb smbs smtp smtps
telnet tftp
Features: alt-svc AsynchDNS brotli GSS-API HSTS HTTP2 HTTPS-proxy IDN
IPv6 Kerberos Largefile libz NTLM NTLM_WB PSL SPNEGO SSL TLS-SRP
UnixSockets zstd

fio NOT running:

% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 83.6M 0 --:--:-- 0:00:57 --:--:-- 87.0M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 82.8M 0 --:--:-- 0:00:57 --:--:-- 79.1M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 82.7M 0 --:--:-- 0:00:57 --:--:-- 89.7M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 87.4M 0 --:--:-- 0:00:54 --:--:-- 94.3M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 88.1M 0 --:--:-- 0:00:54 --:--:-- 94.7M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 82.6M 0 --:--:-- 0:00:57 --:--:-- 83.9M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 86.4M 0 --:--:-- 0:00:55 --:--:-- 90.1M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 82.8M 0 --:--:-- 0:00:57 --:--:-- 67.5M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 83.4M 0 --:--:-- 0:00:57 --:--:-- 78.7M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 84.0M 0 --:--:-- 0:00:56 --:--:-- 87.4M

fio running:

% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 86.7M 0 --:--:-- 0:01:11 --:--:-- 88.7M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 87.7M 0 --:--:-- 0:00:54 --:--:-- 93.5M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 88.5M 0 --:--:-- 0:00:53 --:--:-- 95.1M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 91.6M 0 --:--:-- 0:00:52 --:--:-- 94.4M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 89.4M 0 --:--:-- 0:00:53 --:--:-- 86.6M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 88.6M 0 --:--:-- 0:00:53 --:--:-- 84.8M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 84.6M 0 --:--:-- 0:00:56 --:--:-- 87.5M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 86.9M 0 --:--:-- 0:00:54 --:--:-- 81.4M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 89.0M 0 --:--:-- 0:00:53 --:--:-- 86.4M
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4768M 0 4768M 0 0 91.1M 0 --:--:-- 0:00:52 --:--:-- 90.6M