[rrd-developers] rrdcached performance problem

Sebastian Harl sh at tokkee.org
Thu Oct 29 09:40:05 CET 2009


On Wed, Oct 28, 2009 at 11:25:03PM -0700, Thorsten von Eicken wrote:
> it's clearly active both receiving and flushing, and realloc is the
> top primitive that I see. Mhhh, I haven't dealt with these things in
> eons so I'll have to see whether there's a different distro I can use
> to get a better realloc implementation.

Disclaimer: I have not looked into the whole issue in detail yet, this
is just a more or less wild guess … ;-)

You're on Linux, right? So, I presume, you're using the GNU libc. IIrc,
the glibc memory management implementation (*alloc, free) is optimized
for memory usage rather than speed, so the speed is (supposedly - did
not check that myself) rather slow.

This might also further explain why Kevin did not stumble across that
issue, since (iIrc) he's on FreeBSD which might have a "better" (speed-
wise) implementation of those functions.

Since we're using the glib (as in GNOME lib - note the missing 'c' ;-))
anyway, we might give it a try to use their memory management functions
(g_*malloc*, g_free) - those are supposed to be quite a bit faster (yet,
I did not check that myself neither).


Sebastian "tokkee" Harl +++ GnuPG-ID: 0x8501C7FC +++ http://tokkee.org/

Those who would give up Essential Liberty to purchase a little Temporary
Safety, deserve neither Liberty nor Safety.         -- Benjamin Franklin

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