Date: Sun, 10 Sep 1995 10:09:44 -0700 From: David Greenman <davidg@Root.COM> To: jleppek@suw2k.ess.harris.com (James Leppek), freebsd-current@freefall.freebsd.org Subject: Re: Sig 11 and -current problems. Message-ID: <199509101709.KAA02726@corbin.Root.COM> In-Reply-To: Your message of "Sun, 10 Sep 95 09:54:40 PDT." <199509101654.JAA02698@corbin.Root.COM>
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>>I do not think there is a "one pass" solution for the current problem.
>>I am also a little puzzled as to how the VM changes(if they are at fault)
>>can cause such pervasive problems??? I would have thought they would
>>be isolated inside the kernel and outside of most of the binaries...
>
> Among John's changes were some to the way that fault clusters work. When the
>system does clustering, it must determine the number of contiguous blocks on
>the disk. If it calculates this number too large, it will page in some garbage.
>Once this gets paged in, it will "stick" in the cache until it is flushed. The
>affect of this is that machines with lots of memory will tend to work better
^^^^^^
Should be "worse". Sory about that...
>than machines with small amounts of memory (because the small memory machines
>will flush out the garbage quickly and/or do less aggressive clustering -
>avoiding the problem completely).
> The problem *might* be in the new ffs_bmap() routine that now calculates
>the amount of "run behind" (the amount of contiguous pages before the
>requested block). In any case, the problem sounds very much to be either in
>the vnode_pager or related routines (ffs_bmap, etc). I don't have time to look
>into this at the moment, but perhaps John will be able to some time soon.
>
>-DG
-DG
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