Messages in this thread Patch in this message |  | | From | Mel Gorman <> | Subject | [PATCH 3/4] mm: Gather more PFNs before sending a TLB to flush unmapped pages | Date | Wed, 15 Apr 2015 11:42:55 +0100 |
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The patch "mm: Send a single IPI to TLB flush multiple pages when unmapping" would batch 32 pages before sending an IPI. This patch increases the size of the data structure to hold a pages worth of PFNs before sending an IPI. This is a trade-off between memory usage and reducing IPIS sent. In the ideal case where multiple processes are reading large mapped files, this patch reduces interrupts/second from roughly 180K per second to 60K per second.
Signed-off-by: Mel Gorman <mgorman@suse.de> --- include/linux/sched.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h index 9d51841806f4..abff66ecc302 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1275,11 +1275,16 @@ enum perf_event_task_context { perf_nr_task_contexts, }; -/* Matches SWAP_CLUSTER_MAX but refined to limit header dependencies */ -#define BATCH_TLBFLUSH_SIZE 32UL +/* + * Use a page to store as many PFNs as possible for batch unmapping. Adjusting + * this trades memory usage for number of IPIs sent + */ +#define BATCH_TLBFLUSH_SIZE \ + ((PAGE_SIZE - sizeof(struct cpumask) - sizeof(unsigned long)) / sizeof(unsigned long)) /* Track pages that require TLB flushes */ struct unmap_batch { + /* Update BATCH_TLBFLUSH_SIZE when adjusting this structure */ struct cpumask cpumask; unsigned long nr_pages; unsigned long pfns[BATCH_TLBFLUSH_SIZE]; -- 2.1.2
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