Date: Mon, 7 Jul 2003 21:57:27 -0700 (PDT) From: Don Lewis <truckman@FreeBSD.org> To: silby@FreeBSD.org Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/kern subr_param.c sys_pipe.c src/sys/sys pipe.h Message-ID: <200307080457.h684vRM7009343@gw.catspoiler.org> In-Reply-To: <200307080402.h6842VtT064702@repoman.freebsd.org>
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On 7 Jul, Mike Silbersack wrote: > silby 2003/07/07 21:02:31 PDT > > FreeBSD src repository > > Modified files: > sys/kern subr_param.c sys_pipe.c > sys/sys pipe.h > Log: > Put some concrete limits on pipe memory consumption: > > - Limit the total number of pipes so that we do not > exhaust all vm objects in the kernel map. When > this limit is reached, a ratelimited message will > be printed to the console. > > - Put a soft limit on the amount of memory consumable > by pipes. Once the limit has been reached, all new > pipes will be limited to 4K in size, rather than the > default of 16K. > > - Put a limit on the number of pages that may be used > for high speed page flipping in order to reduce the > amount of wired memory. Pipe writes that occur > while this limit is exceeded will fall back to > non-page flipping mode. > > The above values are auto-tuned in subr_param.c and > are scaled to take into account both the size of > physical memory and the size of the kernel map. > > These limits help to reduce the "kernel resources exhausted" > panics that could be caused by opening a large > number of pipes. (Pipes alone are no longer able > to exhaust all resources, but other kernel memory hogs > in league with pipes may still be able to do so.) There should probably be a per-user limit(s) as well. At a minimum, the number of pipes per user should be limited. The limit should be stored in struct plimit, and the current usage should be tracked in struct uidinfo.home | help
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