On 05/14/2012 08:58 PM, ehrhardt@xxxxxxxxxxxxxxxxxx wrote: > From: Christian Ehrhardt <ehrhardt@xxxxxxxxxxxxxxxxxx> > > 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> > --- > Documentation/sysctl/vm.txt | 12 ++++++++++-- > 1 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt > index 96f0ee8..4d87dc0 100644 > --- a/Documentation/sysctl/vm.txt > +++ b/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 (if > +available) are read in from swap in a single attempt. This is the swap "If available" would be wrong in next kernel because recently Rik submit following patch, mm: make swapin readahead skip over holes http://marc.info/?l=linux-mm&m=132743264912987&w=4 > +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 Otherwise, Looks good to me. -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>