Re: stat very inefficient

[Peter Chubb]

>>>>> "Andrew" == Andrew Morton <akpm@xxxxxxxx> writes:

Andrew> Paul Jackson <pj@xxxxxxx> wrote:
>>  Andrew wrote: > hmm.  Here's a Pentium III profile ...
>> 
>> What conclusion do your draw from this profile?

Andrew> At a quick squint: we spend about 10% of total system time in
Andrew> those copy functions.  If we halve their runtime (which would
Andrew> be good), we don't gain much.

And the proposal only removes one of the three copies, so you're
probably looking at around a 30% rather than a 50% reduction in the
10%.  Plus whatever knock on effects there might be from different
cache usage.

Is it worth the effort, and added complexity?  Unless there's some
other architecture where the memcpys are really expensive, the answer
at present appears to be, no.

--
Dr Peter Chubb  http://www.gelato.unsw.edu.au  peterc AT gelato.unsw.edu.au
The technical we do immediately,  the political takes *forever*
 





-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/