From: Daniel Santos <daniel.santos@pobox.com>
To: cygwin@cygwin.com
Subject: long I/O delays when strace is running
Date: Thu, 20 Apr 2017 18:13:00 -0000 [thread overview]
Message-ID: <be8713ec-5b68-e0e9-c5a5-d48fce491a2d@pobox.com> (raw)
Well I've solved one problem, but now I have another one. To try to
understand why except is getting broken pipes (child processes are
"going away"), I modified DejaGNU's /usr/bin/runtest so that it would
strace each except process:
-exec "$expectbin" $debug -- "$runpath"/runtest.exp $target ${1+"$@"}
+exec strace --output=/tmp/runtest.$$.log --trace-children
--mask=startup $expectbin $debug -- $runpath/runtest.exp $target ${1+"$@"}
However, when I run make -kj8 check after this, Cygwin processes that do
file I/O and even ps become very unresponsive and CPU utilization is low
(not to say that DejaGNU is good at balancing the test load). If I hit
ctrl-C on the make process, it won't exit for somewhere around 30
seconds. I am able to reproduce this to some degree with this simple
snippet, although the delays aren't as long as doing the above:
for ((i = 0; i < 64; ++i)); do strace --output=/tmp/sleep.$$.log
--trace-children --mask=startup sleep 64; done
Can anybody try this and see if they get delays when running ps -ef or
some such?
Thanks,
Daniel
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next reply other threads:[~2017-04-19 23:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-20 18:13 Daniel Santos [this message]
2017-04-21 0:11 ` Gluszczak, Glenn
2017-04-21 7:57 ` Daniel Santos
2017-04-21 9:38 ` Daniel Santos
2017-04-21 11:06 ` Daniel Santos
2017-04-21 12:08 ` Mark Geisert
2017-04-21 18:23 ` Daniel Santos
2017-04-22 15:24 ` Mark Geisert
2017-04-23 12:58 ` Daniel Santos
2017-04-23 18:15 ` Mark Geisert
2017-04-24 8:23 ` Daniel Santos
2017-04-24 9:24 ` Daniel Santos
2017-04-24 9:34 ` Mark Geisert
2017-04-24 15:00 ` Daniel Santos
2017-04-24 19:30 ` Daniel Santos
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