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% Registration Can you handle the pressure? Making Linux
% bulletproof under load
% Martin J Bligh (mbligh@aracnet.com)
Operating under memory pressure has been a
persistent problem for Linux customers.
Despite significant work done in the 2.6
kernel to improve its handling of memory, it
is still easy to make the Linux kernel slow to
a crawl or lock up completely under load.
One of the fundamental sources for memory
pressure is the filesystem pagecache usage,
along with the \ident{buffer_head} entries that
control them. Another problem area is inode
and dentry cache entries in the slab cache.
Linux struggles to keep either of these under
control. Userspace processes provide another
obvious source of memory usage, which are
partially handled by the OOM killer subsystem,
which has often been accused of making poor
decisions on which process to kill.
This paper takes a closer look at various
scenerios causing of memory pressure and the
way VM handles it currently, what we have done
to keep the system for falling apart. This
paper also discusses the future work that
needs to be done to improve further, which may
require careful re-design of subsystems.
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