Re: [Crash-utility] [PATCH 0/4] speed up handling of dumps with many tasks
On Fri, Apr 6, 2018 at 9:10 AM Dave Anderson <anderson(a)redhat.com> wrote:
----- Original Message -----
> This series decreases crash startup and 'ps' processing time when
handling dumps
> with many tasks. Prior to the series a 1M task dump took 45m to
load
and 45m
> more to run ps. Once patched, startup+ps time drops below 40
seconds.
Hi Greg,
This sounds really good, although I have to say I've never
encountered a
dumpfile
that had such a large task count. I will review and test the
patch-set
next week.
Thanks.
BTW, did you test this on a live system that has such a large task
count?
Like for example, as I recall, the task_exists() checks that you removed
are
checking for tasks that were found when scanning the lists, but gone
by
the
time it got around to storing them.
I have used these patches on a live machine. 'ps' runs and appears
correct. Though it's a moving target, so difficult to say if every line is
perfect. I don't see any duplicates. And I see a similar set of pids to
what /bin/ps reports. Though /bin/ps consistently reports a subset (~1000
fewer pids than crash reports). For these /bin/ps-mising pids, they are
visible in /proc/$pid and "kill -0 $pid" also works. So I think it's a
either a procfs bug or /bin/ps bug. stracing /bin/ps doesn't show any
syscall errors.