On Thu, 7 Feb 2002, yodaiken wrote:
> So what's the difference between combi_spin and combi_mutex?
> combi_spin becomes
> if not mutex locked, spin
> else sleep
> Bizzare
no, the real optimization is that when spin meets spin, they will not
mutex. If a mutex-user has it then spins turn into mutex, but that (is
supposed to) happen rarely.
i think one example *could* be to turn inode->i_sem into a combi-lock. Eg.
generic_file_llseek() could use the spin variant.
this is a real performance problem, i've seen scheduling storms in
dbench-type runs due to llseek taking the inode semaphore.
whether combi-locks truly bring performance benefits remains to be seen,
but the patch definitely needs to provide some working example and some
hard numbers for some real workload.
Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Thu Feb 07 2002 - 21:01:06 EST