Messages in this thread | | | From | Al Boldi <> | Subject | Re: [PATCH 1/1] threads_max: Simple lockout prevention patch | Date | Mon, 24 Apr 2006 17:46:42 +0300 |
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Pekka Enberg wrote: > On 4/24/06, Al Boldi <a1426z@gawab.com> wrote: > > > > Like so? > > > > if (nr_threads >= max_threads) > > > > if (p->pid != su_pid) > > > > goto bad_fork_cleanup_count; > > > > > > It's better to combine the two if statements into one with &&. > > > I thought of combining them too, but was afraid of some compile > > optimization issues. Remember, this code-path is executed for each and > > every fork in the system, thus it's highly performance sensitive. > > There shouldn't be any difference.
There shouldn't, if things were perfect.
> What compiler optimizations are you referring to?
-O3 at least.
> Did you study the generated object code?
Not really.
But -O3 creates faster code w/ some strange flaws like failing nfs-boot. Maybe that's fixed in the latest gcc, but gcc-3.2.2 was exhibiting this bug. So this doesn't really help a developer to be confident about compiler optimization, thus taking the safe route for performance sensitive code-paths.
Thanks!
-- Al
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