Date: Thu, 7 Dec 2000 10:06:43 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: "Daniel C. Sobral" <dcs@newsguy.com> Cc: News History File User <newsuser@free-pr0n.netscum.dk>, hackers@FreeBSD.ORG, usenet@tdk.net Subject: Re: vm_pageout_scan badness Message-ID: <200012071806.eB7I6h410456@earth.backplane.com> References: <200012011918.eB1JIol53670@earth.backplane.com> <200012020525.eB25PPQ92768@newsmangler.inet.tele.dk> <200012021904.eB2J4An63970@earth.backplane.com> <200012030700.eB370XJ22476@newsmangler.inet.tele.dk> <200012040053.eB40rnm69425@earth.backplane.com> <200012050545.eB55jL453889@crotchety.newsbastards.org> <200012060519.eB65JS910042@crotchety.newsbastards.org> <200012060713.eB67D8I91529@earth.backplane.com> <3A2F4F57.A7EDEAEC@newsguy.com>
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:
:Matt Dillon wrote:
:>
:> You may be able to achieve an effect very similar to mlock(), but
:> runnable by the 'news' user without hacking the kernel, by
:> writing a quick little C program to mmap() the two smaller history
:> files and then madvise() the map using MADV_WILLNEED in a loop
:> with a sleep(15). Keeping in mind that expire may recreate those
:> files, the program should unmap, close(), and re-open()/mmap/madvise the
:> descriptors every so often (like once a minute). You shouldn't have
:> to access the underlying pages but that would also have a similar
:> effect. If you do, use a volatile pointer so GCC doesn't optimize
:> the access out of the loop. e.g.
:
:Err... wouldn't it be better to write a quick little C program that
:mlocked the files? It would need suid, sure, but as a small program
:without user input it wouldn't have security problems.
:
:--
:Daniel C. Sobral (8-DCS)
:dcs@newsguy.com
:dcs@freebsd.org
mlock()ing is dangerous when used on a cyclic file. If you aren't
careful you can run your system out of memory.
-Matt
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