Messages in this thread | | | Subject | Re: [PATCH/RFC] MM slub: add a sysfs entry to show the calculated number of fallback slabs | From | Richard Kennedy <> | Date | Fri, 12 Nov 2010 16:22:44 +0000 |
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On Fri, 2010-11-12 at 09:13 -0600, Christoph Lameter wrote: > On Fri, 12 Nov 2010, Richard Kennedy wrote: > > > On my desktop workloads (kernel compile etc) I'm seeing surprisingly > > little slab fragmentation. Do you have any suggestions for test cases > > that will fragment the memory? > > Do a massive scan through huge amounts of files that triggers inode and > dentry reclaim?
thanks, I'll give it a try.
> > + * Note that this can give the wrong answer if the user has changed the > > + * order of this slab via sysfs. > > Not good. Maybe have an additional counter in kmem_cache_node instead?
I know it's not ideal. Of course there already is a counter in CONFIG_SLUB_STATS but it only counts the total number of fallback slabs issued since boot time. I'm not sure if I can reliably decrement a fallback counter when a slab get freed. If the size was changed then we could have slabs with several different sizes, and off the top of my head I'm not sure if I can identify which ones were created as fallback slabs. I don't suppose there's a spare flag anywhere.
I'll give this some more thought.
regards Richard
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