[Bug libc/11044] malloc dynamic mmap threshold causes 50%-100% increase in memory usage

["tom at atoptech dot com" <sourceware-bugzilla@sourceware.org>]

------- Additional Comments From tom at atoptech dot com  2010-04-07 17:09 -------
Ulrich,

I filed this bug to show, at least for our application, this change did not
result in improved performance. To the contrary, this change increase memory
fragmentation and in some case, memory usage when from 32GB to 64GB when running
our application. Our application ran fine on RedHat release 3 and 4. When we
ported to release 5, memory usage increased with out reason. From our standpoint
we would like the compute platform to be stable from one release to the next.

All I wanted to point out was that after reading the patch comments for this
change, such as,

+  The threshold goes up in value when the application frees memory that was
+  allocated with the mmap allocator. The idea is that once the application
+  starts freeing memory of a certain size, it's highly probable that this is
+  a size the application uses for transient allocations. This estimator
+  is there to satisfy the new third requirement. 

seem to me; weakly justifiable. Some applications may exhibit this behavior,
however, our application does not. And if one going to try and dynamically
adjust the mmap threshold, one should keep adjusting the mmap threshold over the
lifetime of the process and not clamp it so early, i.e., based upon the first
free...

Regards,

Tom Geocaris



-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=11044

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.