The patch titled Subject: documentation: update how page-cluster affects swap I/O has been removed from the -mm tree. Its filename was documentation-update-how-page-cluster-affects-swap-i-o.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Christian Ehrhardt <ehrhardt@xxxxxxxxxxxxxxxxxx> Subject: documentation: update how page-cluster affects swap I/O Fix of the documentation of /proc/sys/vm/page-cluster to match the behavior of the code and add some comments about what the tunable will change in that behavior. Signed-off-by: Christian Ehrhardt <ehrhardt@xxxxxxxxxxxxxxxxxx> Acked-by: Jens Axboe <axboe@xxxxxxxxx> Reviewed-by: Minchan Kim <minchan@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/sysctl/vm.txt | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff -puN Documentation/sysctl/vm.txt~documentation-update-how-page-cluster-affects-swap-i-o Documentation/sysctl/vm.txt --- a/Documentation/sysctl/vm.txt~documentation-update-how-page-cluster-affects-swap-i-o +++ a/Documentation/sysctl/vm.txt @@ -574,16 +574,24 @@ of physical RAM. See above. page-cluster -page-cluster controls the number of pages which are written to swap in -a single attempt. The swap I/O size. +page-cluster controls the number of pages up to which consecutive pages +are read in from swap in a single attempt. This is the swap counterpart +to page cache readahead. +The mentioned consecutivity is not in terms of virtual/physical addresses, +but consecutive on swap space - that means they were swapped out together. It is a logarithmic value - setting it to zero means "1 page", setting it to 1 means "2 pages", setting it to 2 means "4 pages", etc. +Zero disables swap readahead completely. The default value is three (eight pages at a time). There may be some small benefits in tuning this to a different value if your workload is swap-intensive. +Lower values mean lower latencies for initial faults, but at the same time +extra faults and I/O delays for following faults if they would have been part of +that consecutive pages readahead would have brought in. + ============================================================= panic_on_oom _ Patches currently in -mm which might be from ehrhardt@xxxxxxxxxxxxxxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html