[gentoo-user] Re: Steam downloading extremely

[Kai Krakow]

Am Wed, 15 Mar 2017 21:53:44 +0100
schrieb Kai Krakow <hurikhan77@×××××.com>:

> Am Wed, 15 Mar 2017 21:24:10 +0800
> schrieb Danny YUE <sheepduke@×××××.com>:
>
> > Hi guys,
> >
> > I just got Steam installed and running successfully on my machine,
> > and tried to get CS:GO running smoothly, which made me really
> > happy :-D
> >
> > However when Steam is downloading games, the speed is extremely
> > slow, down to several KB/s, even some bytes/s.
> > I have already installed dnsmasq and it *was* good during
> > downloading CS:GO (~4MB/s), but became slow again with Civilization
> > V.
> >
> > I googled a lot but all point to installing dnsmasq, which I don't
> > think is really helpful since I already have done that...
> >
> > Also I'm sure downloading region is correct.
> >
> > Anybody experienced the same issue with dnsmasq installed?
> > Any clue is welcome and thanks in advance.
>
> Here, it's downloading with peak bandwidths of 48 mbytes/s but usually
> it's around 38 mbytes/s. However, I sometimes see slowdowns, too. I
> guess that games are downloaded file by file, and when a lot of small
> files are left in the queue, it just cannot get good bandwidth.
>
> But I only see such slowdowns mostly short before the last few
> megabytes of a game.
>
> Could you check if your downloaded games consist of many smallish
> files? Then that could be the explanation.
>
> You could try activating fq_codel and tcp fastopen:
>
> In /proc/sys/net/ipv4/tcp_fastopen it should say 1.
> In /proc/sys/net/core/default_qdisc it should say fq_codel.
>
> Also, you may want to try out bbr congestion control:
>
> In /proc/sys/net/ipv4/tcp_congestion_control it should say bbr.
>
> By recompiling the kernel, you can reconfigure the defaults for this
> (and enable support). Some of these need modern kernels.
>
> Additionally, many small tcp request need a good portion of your
> upload bandwidth and are very dependent on good round trip times.
> Traditional DSL lines with ping times of 50-60ms can really slow down
> requests of small files a lot due to three-way tcp handshaking, that
> is, you could request only one smallish file per 100-120ms. This can
> totally destroy the usable bandwidth. Maybe watch a running ping
> while the downloads are running. If the ping times increase while the
> download slows down, your bottleneck is the upload.
>
> But also keep in mind that traditional spinning disks may not keep up
> with the bandwidth if confronted with many small files. If you're
> using SSD all should be fine. I'm running on bcache with writeback
> caching which gives a really good performance boost by adding a small
> SSD to one or more big HDDs.

BTW: I don't see how dnsmasq could help you here... It can do nothing
about bandwidth. It only acts as a DNS cache which helps keeping
latency of the DNS resolver down. But this doesn't matter here because
during download, steam won't do many DNS requests.

As already stated, part of the problem may be the upload, and/or bad
queue handling within your broadband router. You can work around it
with a traffic shaper and throttling upload below what's physically
possible with your internet line, thus keeping the queue in front of the
broadband router. That way, a traffic shaper could handle it and work
around bad queue handling.

To resolve the issue it is important to sophistically test the
suggestions one step at a time, starting with the easy ones, and do
your measurements.

-- 
Regards,
Kai

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