2009/10/15 Igor Sobrado <[email protected]>: > On Thu, Oct 15, 2009 at 6:01 AM, Atle Kristensen <[email protected]> wrote: >>> bufcachepercent=90 >> >> I haven't tested (sorry!) but I wonder about the advances? >> Can somebody tell me what's the point of it? :) >> >> /it'll be fun to see what's happening on my machines. :D > > it is all nicely described in Beck's log message. > >
Well, other than the fact that this doesn't do *anything* unless you are cranking bufcachepercent - as the behaviour it is affecting is for when the buffer cache is using more memory than the low water mark of 10% - since the default buffer cache size is 10%, none of this code will kick in normally with a default install. It only matters if you are cranking up your buffer cache size by increasing bufcachepercent in sysctl. If you do that (sysctl -w bufcachepercent=90) then you are telling the system to try to use as much memory as possible for the buffer cache, without getting in the way. This may give you increased performance if you are doing stuff that depends on repeated disk I/O. We *may* at some point in the future increase the bufcachepercent default setting so openbsd does this by default, but for now we would like a lot more people putting real miles on it using the above setting first.
