Gentoo Archives: gentoo-user

From: Michael <confabulate@××××××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Machine hangs up with out of memory
Date: Fri, 30 Apr 2021 10:09:54
Message-Id: 7944779.NyiUUSuA9g@lenovo.localdomain
In Reply to: Re: [gentoo-user] Machine hangs up with out of memory by Adam Carter
1 On Friday, 30 April 2021 02:30:51 BST Adam Carter wrote:
2 > On Wed, Apr 28, 2021 at 7:58 PM Kai Peter <kp@×××××××××××.org> wrote:
3 > > Hi,
4 > >
5 > > I have an issue with a machine where I'm not able to detect the real
6 > > root cause. It hangs up totally. It seems like it was running out of
7 > > memory - but why? Hopefully somebody can give me some insight. As far I
8 > > can see right now, it hangs up a few hours after an `emerge --update
9 > > --newuse --deep --with-bdeps=y @world`.
10 > >
11 > > The machine is an Intel Atom with 8 GB RAM (physical, max) and 24 GB
12 > > swap (a file). So 32 GB RAM in total.
13 >
14 > Might be worth adding zswap using zstd or lz4 to your config (uses more CPU
15 > for less IO)
16 >
18 Zswap will help optimise the swapping of cold pages out of RAM into the
19 compressed zswap cache and eventually push these out to the disk. This won't
20 help with the problem of not having enough RAM to start with for compiling
21 packages with large resource requirements, like e.g. Chromium.
23 With monster packages where more RAM is needed even for a single compilation
24 job, after all cold pages have been swapped out, hot pages will start being
25 swapped out/in. I think at this point the same I/O race condition will ensue
26 as if no zswap were available, plus a compress/decompress CPU load. I guess
27 the point of starting to thrash the on-disk swap trying to free RAM may start
28 sooner, since RAM which would otherwise be available for the single
29 prioritised compilation job is now being used by zswap. So, there would be a
30 sweet spot in using zswap to improve I/O performance, but it could end up
31 becoming a disbenefit on compilation of RAM hungry packages.
33 Please correct my reasoning above if I have misunderstood how zswap works.
35 However, the OP problem here seems to be with a leaky BIND?
37 I found this mentioned upstream - but have not check BGO:
42 > If you want to see which processes are using the most memory, run top then
43 > type 'M' to have top sort by memory instead of CPU. You can also type 'm'
44 > to make top show the memory numbers as an ascii bar graph. The man page
45 > explains what VIRT RES SHR mean.


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Subject Author
Re: [gentoo-user] Machine hangs up with out of memory Kai Peter <kp@×××××××××××.org>
Re: [gentoo-user] Machine hangs up with out of memory Adam Carter <adamcarter3@×××××.com>