3) access to thread-local errno is slow, it's also better to cache it.
Pheww! That is micro-optimization indeed.
Well, thread-local errno might involve a function call on some systems.
If the function call is not CSE'd by the compiler, it means half a
dozen function calls.
Do you have
Paolo Bonzini wrote:
> I actually noticed these in a profile!
What tool do you use for doing profiling on a per-line or per-instruction
basis? The Google profiler?
> 3) access to thread-local errno is slow, it's also better to cache it.
Pheww! That is micro-optimization indeed.
Do you have an o
#ifdef _SC_OPEN_MAX
- if (nfd > sysconf (_SC_OPEN_MAX))
+ static int sc_open_max = -1;
+
+ if (nfd < 0
+ || (nfd > sc_open_max
+ && (sc_open_max != -1
+ || nfd > (sc_open_max = sysconf (_SC_OPEN_MAX)
Doesn't this make poll non-reentrant?
Are there systems wher
Hi Paolo,
* Paolo Bonzini wrote on Wed, Aug 06, 2008 at 10:28:00AM CEST:
> --- a/lib/poll.c
> +++ b/lib/poll.c
> #ifdef _SC_OPEN_MAX
> - if (nfd > sysconf (_SC_OPEN_MAX))
> + static int sc_open_max = -1;
> +
> + if (nfd < 0
> + || (nfd > sc_open_max
> + && (sc_open_max != -1
> +
I actually noticed these in a profile!
1) sysconf (_SC_OPEN_MAX) is slow, it's better to cache it.
2) division by 1000 is slow, and in my code the timeout was always 0.
3) access to thread-local errno is slow, it's also better to cache it.
Ciao,
Paolo
2008-08-06 Paolo Bonzini <[EMAIL PROTEC
