Messages in this thread | | | Subject | Re: Kernel is unstable | From | Christoph Rohland <> | Date | 02 Mar 2001 09:23:21 +0100 |
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Hi Linus,
On 1 Mar 2001, Linus Torvalds wrote: > Note how do_brk() does the merging itself (see the comment "Can we > just expand an old anonymous mapping?"), and that it's basically > free when done that way, with no worries about locking etc. The same > could be done fairly trivially in mmap too, but I never saw any real > usage patterns that made it look all that worthwhile (*). Handling > the mmap case the same way do_brk() does it would fix the behaviour > of this pathological example too..
Oh there is at least one application, which does trigger the merging quite often: SAP R/3. We have a big memory area which is handled in 1M blocks which get mmaped/munmapped/mprotected all the time. This now leads to a really big avl tree which before has been much smaller.
I am not sure that the merging is a gain since it in itself is a overhead and we work on fixed blocks. I simply wanted to point out that there are applications out there which trigger it.
Greetings Christoph
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