Messages in this thread | | | Date | Tue, 6 Apr 1999 14:58:17 -0700 (PDT) | From | Simon Kirby <> | Subject | Re: [patch] arca-vm-2.2.5 |
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On Tue, 6 Apr 1999, Stephen C. Tweedie wrote:
> On Tue, 6 Apr 1999 15:04:36 +0200 (CEST), Andrea Arcangeli > <andrea@e-mind.com> said: > > > I also think that I'll implement the cookie thing suggested by Mark since > > I am too much courious to see how much it will help (even if my mind is > > driven by RB-trees ;). > > Trees are bad for this sort of thing in general: they can be as fast as > hashing for lookup, but are much slower for insert and delete > operations. Insert and delete for the page cache _must_ be fast. > Expanding a hash table does not cost enough to offset the performance > problems.
I wrote some sysreq extensions that printk bucket counts for the hash tables a while back. Want me to dig them up? (I since run my kernels with hash tables 4x-16x as large -- not sure how much it helps, though.) I noticed what sct was talking about where when it hits swap, things tend to all go into buckets close together -- I saw hundreds of things linked to the same buckets at one point after I made my machine hit swap a bit.
I implemented inode, dentry, and page hash dumping, but I could stick in buffers too.
Simon-
| Simon Kirby | Systems Administration | | mailto:sim@netnation.com | NetNation Communications | | http://www.netnation.com/ | Tech: (604) 684-6892 |
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