Messages in this thread | | | Subject | [RFCv2][PATCH 0/5] mm: Batch page reclamation under shink_page_list | From | Dave Hansen <> | Date | Thu, 16 May 2013 13:34:27 -0700 |
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These are an update of Tim Chen's earlier work:
http://lkml.kernel.org/r/1347293960.9977.70.camel@schen9-DESK
I broke the patches up a bit more, and tried to incorporate some changes based on some feedback from Mel and Andrew.
Changes for v2: * use page_mapping() accessor instead of direct access to page->mapping (could cause crashes when running in to swap cache pages. * group the batch function's introduction patch with its first use * rename a few functions as suggested by Mel * Ran some single-threaded tests to look for regressions caused by the batching. If there is overhead, it is only in the worst-case scenarios, and then only in hundreths of a percent of CPU time.
If you're curious how effective the batching is, I have a quick and dirty patch to keep some stats:
https://www.sr71.net/~dave/intel/rmb-stats-only.patch
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To do page reclamation in shrink_page_list function, there are two locks taken on a page by page basis. One is the tree lock protecting the radix tree of the page mapping and the other is the mapping->i_mmap_mutex protecting the mapped pages. This set deals only with mapping->tree_lock.
Tim managed to get 14% throughput improvement when with a workload putting heavy pressure of page cache by reading many large mmaped files simultaneously on a 8 socket Westmere server.
I've been testing these by running large parallel kernel compiles on systems that are under memory pressure. During development, I caught quite a few races on smaller setups, and it's being quite stable that large (160 logical CPU / 1TB) system.
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