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[Bug libc/1128] Malloc not trimming filled-up sbrk space causes unnecessary system call overhead
- From: "bugzilla1 at malloc dot de" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: 1 Oct 2009 17:14:51 -0000
- Subject: [Bug libc/1128] Malloc not trimming filled-up sbrk space causes unnecessary system call overhead
- References: <20050727134634.1128.jp-www@dcs.gla.ac.uk>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From bugzilla1 at malloc dot de 2009-10-01 17:14 -------
In reply to comment #5:
The test program you've posted does potentially cause lots of system calls, but
for a different reason than the original report:
You're allocating 256k blocks which exceed the default mmap threshold.
So, to avoid any mmapping in that kind of app you have to specify _both_
mallopt(M_TRIM_THRESHOLD, (unsigned long) -1);
mallopt(M_MMAP_THRESHOLD, (unsigned long) -1);
--
http://sourceware.org/bugzilla/show_bug.cgi?id=1128
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