On Sat, Jul 30, 2011 at 1:38 AM, Mattieu Baptiste <[email protected]> wrote: > On Fri, Jul 29, 2011 at 11:58 PM, Ted Unangst <[email protected]> wrote: >> On Fri, Jul 29, 2011, Mattieu Baptiste wrote: >> >>> After digging around this problem with help from Pedro, I noticed that >>> a 4.9-release kernel works ok, whereas a 5.0-beta does not. So I tried >>> to identify which commit was responsible and found out this one is >>> responsible of *very* slow writes with softdep (I only have this bug >>> on sparc64): >>> http://marc.info/?l=openbsd-cvs&m=130730313107059&w=2 >>> >>> I can add that this bug is just affecting softdep: >>> - dd'ing to the raw device is fast, >>> - dd'ing to the file system mounted sync is very fast, >>> - dd'ing to the file system mounted async is very fast, >>> - dd'ing to the file system mounted with softdep is very slow. >>> >>> I can also add that changing a working kernel to bufcachepercent >=42 >>> via sysctl is ok too. >> >> What happens if you change bufcachepercent to a much smaller value, like >> the 4.9 default? > > If I change kern.bufcachepercent via sysctl to 10 or 5, it's still very slow.
But... if I set BUFCACHEPERCENT to 10 in sys/conf/param.c, softdep is fast again. -- Mattieu Baptiste "/earth is 102% full ... please delete anyone you can."
