Re: Low TCP throughput due to vmpressure with swap enabled

From: Yu Zhao
Date: Wed Nov 23 2022 - 20:29:47 EST

On Wed, Nov 23, 2022 at 6:18 PM Yu Zhao <yuzhao@xxxxxxxxxx> wrote:
>
> On Wed, Nov 23, 2022 at 2:22 PM Johannes Weiner <hannes@xxxxxxxxxxx> 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@xxxxxxxxxxx>
>
> 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

This is the baseline kernel, not MGLRU.

> $ 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