david at kineticode
Aug 23, 2006, 2:33 PM
Post #1 of 1
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Fellow Bricoleurs,
If you're running Bricolage on a box using the 2.6 Linux kernel and
rely on Apache::SizeLimit to manage memory control, be sure that you
read this bit of the docs for the latest version of Apache::SizeLimit
(0.9):
=head2 linux
For linux we read the process size out of F</proc/self/statm>. If you
are worried about performance, you can consider using C<<
Apache::SizeLimit->set_check_interval() >> to reduce how often this
read happens.
As of linux 2.6, F</proc/self/statm> does not report the amount of
memory shared by the copy-on-write mechanism as shared memory. This
means that decisions made based on shared memory as reported by that
interface are inherently wrong.
However, as of the 2.6.14 release of the kernel, there is
F</proc/self/smaps> entry for each process. F</proc/self/smaps>
reports various sizes for each memory segment of a process and allows
us to count the amount of shared memory correctly.
If C<Apache::SizeLimit> detects a kernel that supports
F</proc/self/smaps> and the C<Linux::Smaps> module is installed it
will use that module instead of F</proc/self/statm>.
Reading F</proc/self/smaps> is expensive compared to
F</proc/self/statm>. It must look at each page table entry of a
process. Further, on multiprocessor systems the access is
synchronized with spinlocks. Again, you might consider using C<<
Apache::SizeLimit->set_check_interval() >>.
Also, in order for 0.09 to work with Bricolage, you'll need to apply
this patch (it will be in the next version of Apache::SizeLimit):
http://marc.theaimsgroup.com/?l=apache-modperl-dev&m=115438042519704
Best,
David
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