Re: Another crash with 2.1.42 + mmap patches

David S. Miller (
Wed, 11 Jun 1997 20:27:50 -0400

Date: Wed, 11 Jun 1997 12:17:18 +0100 (BST)
From: Mark Hemment <markhe@sco.COM>

I just put some printk()s into kmem_cache_create(), and they show
the 2048 and 4096 general-caches use an order of 2 which certainly
isn't enormous. Were you using debugging support (ie. red-zoning)
when you obtained your figures? Perhaps there is a problem
there.... Maybe you have 8196byte pages? I'll re-check the maths.

order 2 is 4 pages, that is too much and risks allocation failures
even when much memory is available. Any attempt to rely on generic
allocations for a major subsystem which grabs more than 2 pages at a
time from gfp() is asking for big trouble.

In terms of the fragmentation behavior of the buddy system page
allocator we have, order 2 _is_ in fact enormous.

Yow! 11.26 MB/s remote host TCP bandwidth & ////
199 usec remote TCP latency over 100Mb/s ////
ethernet. Beat that! ////
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David S. Miller, /_____________/ / // /_/ ><