Date: Wed, 9 Dec 2009 09:07:33 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Linda Messerschmidt <linda.messerschmidt@gmail.com> Subject: Re: Superpages on amd64 FreeBSD 7.2-STABLE Message-ID: <200912090907.33433.jhb@freebsd.org> In-Reply-To: <237c27100911260714x2fcb194ew1e6ce11e764efd08@mail.gmail.com> References: <237c27100911260714x2fcb194ew1e6ce11e764efd08@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thursday 26 November 2009 10:14:20 am Linda Messerschmidt wrote: > It's not clear to me if this might be a problem with the superpages > implementation, or if squid does something particularly horrible to > its memory when it forks to cause this, but I wanted to ask about it > on the list in case somebody who understands it better might know > whats going on. :-) I talked with Alan Cox some about this off-list and there is a case that can cause this behavior if the parent squid process takes write faults on a superpage before the child process has called exec() then it can result in superpages being fragmented and never reassembled. Using vfork() should prevent this from happening. It is a known issue, but it will probably be some time before it is addressed. There is lower hanging fruit in other areas in the VM that will probably be worked on first. -- John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200912090907.33433.jhb>