Messages in this thread | | | Date | Thu, 15 Jan 2015 00:40:46 +0200 | From | "Kirill A. Shutemov" <> | Subject | Re: [RFC][PATCH] procfs: Add /proc/<pid>/mapped_files |
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On Tue, Jan 13, 2015 at 04:20:29PM -0800, Calvin Owens wrote: > Commit b76437579d1344b6 ("procfs: mark thread stack correctly in > proc/<pid>/maps") introduced logic to mark thread stacks with the > "[stack:%d]" marker in /proc/<pid>/maps. > > This causes reading /proc/<pid>/maps to take O(N^2) time, where N is > the number of threads sharing an address space, since each line of > output requires iterating over the VMA list looking for ranges that > correspond to the stack pointer in any task's register set. When > dealing with highly-threaded Java applications, reading this file can > take hours and trigger softlockup dumps. > > Eliminating the "[stack:%d]" marker is not a viable option since it's > been there for some time, and I don't see a way to do the stack check > more efficiently that wouldn't end up making the whole thing really > ugly.
Can we find stack for threads once on seq_operations::start() and avoid for_each_thread() on seq_operations::show() for each stack vma?
-- Kirill A. Shutemov
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