In bug 670596 comment 89, Igor wrote: > (In reply to Justin Lebar [:jlebar]) >> The stricter decommit is not needed with MADV_DONTNEED on Linux. On Linux, >> MADV_DONTNEED'ed pages don't count against your RSS. > > I saw few times on Linux that when GC decommits, say, 300, MB of pages, then RSS shrinks > just by 30-50 MB max. Does MADV_DONTNEED really works on Linux as advertised? To which I responded: > Perhaps not! Or perhaps its behavior is different in the browser than in the simple > tests I've run. (It's also possible that 250mb of the 300mb decommitted was not in > physical memory.) We can do a simple test of MADV_DONTNEED: Define MALLOC_DOUBLE_DECOMMIT in jemalloc for Linux, then modify nsMemoryReporterManager's implementation of the |resident| memory reporter so it calls malloc_purge_freed_pages() before reading the RSS on Linux, as we do on Mac. Now open a bunch of tabs, close all but one, and record Firefox's resident size using top or some other external program. Then open about:memory and observe if the RSS falls.
Hugh, if you run Linux, would you be interested in checking this out?
(In reply to Justin Lebar [:jlebar] from comment #1) > Hugh, if you run Linux, would you be interested in checking this out? I will check this. However it would be nice if the Minimize memory usage in about:memory would run the shrinking GC. I will file a bug about that.
> I will file a bug about that. Bug 699279.
Assignee: nobody → igor
Whiteboard: [MemShrink][mentor=jlebar] → [MemShrink]
Whiteboard: [MemShrink] → [MemShrink:P2]
Status: NEW → RESOLVED
Last Resolved: 6 years ago
Resolution: --- → WORKSFORME
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