futexes and massive malloc(9) use

Alexander Best arundel at freebsd.org
Tue Dec 14 22:30:34 UTC 2010


hi there,

i just stumbled upon the fact that vmstat -m reports a massive amount of
malloc(9) requests coming from futexes. for me it's higher than any other type.
also every request made is only 128 bytes. these calls seem to be responsible
for this:

linux_futex.c:193:		tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
linux_futex.c:223:		*wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);

the #requests are ~ 5 billion with uptime reporting ~ 3 days.

might this be one of the reasons for the performance issues with flash e.g.?

cheers.
alex

-- 
a13x


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