[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
One case of memory pressure
From: |
Thomas Schwinge |
Subject: |
One case of memory pressure |
Date: |
Tue, 29 May 2012 21:25:34 +0200 |
User-agent: |
Notmuch/0.9-101-g81dad07 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
Hi!
Just a quick report regarding recovering from memory pressure. This is
with gnumach-image-1.3.99-486-dbg 2:1.3.99.dfsg.git20120219-1.
During GCC testing, my system collapsed. Unfortunately, there was no
farewell note found. Re-running the offending (I suppose) test manually,
»[...]master.build/gcc/xgcc -B[...]/master.build/gcc/
-fno-diagnostics-show-caret -O2 -w -c -o limits-structnest.o
[...]/master/gcc/testsuite/gcc.c-torture/compile/limits-structnest.c«, I
see that it within its few seconds of run time it nearly completely sucks
up of what vmstat reports as free memory. (Running it manually now,
there is no system crash, unfortunately (?).) OK, then lets start two of
these in parallel; here is what happens after a few seconds:
$ vmstat
pagesize: 4096
size: 1005M
free: 196K
active: 331M
inactive: 664M
wired: 10.2M
zero filled: 6474M
reactivated: 960M
pageins: 51.4M
pageouts: 623M
page faults: 2086694
cow faults: 37881
memobj hit ratio: 90%
swap size: 954M
swap free: 345M
Free memory dashed to the ground, and heavy swap usage. After perhaps
half a minute the two processes finish, and the system completely
recovers, it seems:
$ vmstat
pagesize: 4096
size: 1005M
free: 983M
active: 7380K
inactive: 5572K
wired: 9.87M
zero filled: 6505M
reactivated: 960M
pageins: 56.5M
pageouts: 624M
page faults: 2099404
cow faults: 38418
memobj hit ratio: 90%
swap size: 954M
swap free: 923M
RUnning four in parallel, the system started heavy thrashing, I got some
error of sigpost (?) in the shell where I ran vmstat, which then froze, I
instructed another shell to kill the four GCC processes, three of which
got killed, then the screen session exploded. Logging in anew, the
system has recovered again:
$ vmstat
pagesize: 4096
size: 1005M
free: 953M
active: 23.5M
inactive: 16.7M
wired: 11.8M
zero filled: 7884M
reactivated: 1922M
pageins: 95.4M
pageouts: 856M
page faults: 2663565
cow faults: 57758
memobj hit ratio: 93%
swap size: 954M
swap free: 924M
Quite nice! (Unfortunately that doesn't tell me why it hung during GCC
testing, though.)
While there have been changes "recently" to GCC's internal memory
management, I do not think these contribute to the test failure/system
crash, because the same pattern of using up nearly 1 GiB and then
finishing successfully is also seen when running the test with the
system's GCC 4.4/4.5/4.6 compilers. And the test itself is as old as
2007. Bad luck, probably.
Grüße,
Thomas
pgp5LQklzUOeV.pgp
Description: PGP signature
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- One case of memory pressure,
Thomas Schwinge <=