Messages in this thread | | | Date | Sun, 1 Jul 2012 09:02:28 +0200 | From | Markus Trippelsdorf <> | Subject | Re: Leap second insertion causes futex to repeatedly timeout |
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On 2012.07.01 at 02:57 +0200, Jan Engelhardt wrote: > > This year's leap second insertion has had the strange effect on at least > Linux versions 3.4.4 (my end) and 3.5-rc4 (Simon's box, Cc) that certain > processes use up all CPU power, because of futexes repeatedly timing > out. This seems to only affect certain processes. > > Simon observes - http://s85.org/owXfmLvt - that > Firefox/Thunderbird/Chrome/Java are affected.
On my ntp synchronized Linux 3.5 testbox I saw a similar issue.
The leap second was successfully inserted last night: Jul 1 01:59:59 x4 kernel: Clock: inserting leap second 23:59:60 UTC
Because glibc-2.16 was released yesterday I've build it this morning. During "make check" I saw several mutex related tests failures. For example /nptl/tst-mutex5a.c failed with a "premature timeout difference" of one second.
tst-mutex5a.c: #define TYPE PTHREAD_MUTEX_ADAPTIVE_NP #include "tst-mutex5.c"
from tst-mutex5.c: // ... gettimeofday (&tv, NULL); TIMEVAL_TO_TIMESPEC (&tv, &ts);
ts.tv_sec += 2; /* Wait 2 seconds. */
err = pthread_mutex_timedlock (&m, &ts); // ... { int clk_tck = sysconf (_SC_CLK_TCK);
gettimeofday (&tv2, NULL);
tv2.tv_sec -= tv.tv_sec; tv2.tv_usec -= tv.tv_usec; if (tv2.tv_usec < 0) { tv2.tv_usec += 1000000; tv2.tv_sec -= 1; }
/* Be a bit tolerant, add one CLK_TCK. */ tv2.tv_usec += 1000000 / clk_tck; if (tv2.tv_usec >= 1000000) { tv2.tv_usec -= 1000000; ++tv2.tv_sec; }
if (tv2.tv_sec < 2) { printf ("premature timeout: %ld.%06ld difference\n", tv2.tv_sec, tv2.tv_usec); return 1; } } // ...
-- Markus
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