Date: Thu, 03 Mar 2005 22:37:19 +0800 From: David Xu <davidxu@freebsd.org> To: Ryan Sommers <ryans@gamersimpact.com> Cc: David Schultz <das@freebsd.org> Subject: Re: Removing kernel thread stack swapping Message-ID: <4227211F.5070505@freebsd.org> In-Reply-To: <42271B6A.4070802@gamersimpact.com> References: <20050303074242.GA14699@VARK.MIT.EDU> <42271B6A.4070802@gamersimpact.com>
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Ryan Sommers wrote: > David Schultz wrote: > >> Any objections to the idea of removing the feature of swapping out >> kernel stacks? Unlike disabling UAREA swapping, this has the >> small downside that it wastes 16K (give or take a power of 2) of >> wired memory per kernel thread that we would otherwise have >> swapped out. However, this disadvantage is probably negligible by >> today's standards, and there are several advantages: > > > I like the idea of fixing a lot of possible panics. However, I don't > know if we should nix it completely. Wasting this little memory won't > hurt anyone on a contemporary computer. However, our embedded systems > folks don't look at memory in the same light, and 16K here or there > can begin to really add up in a memory tight architecture. Of course > it could be argued that embedded systems probably don't have many > threads, many threads that can be swapped, or even swap space in the > first place. > > I guess it's a judgment call that one of our embedded systems > engineers could better answer. > Does your embedded system has swap device ? I have joined some embedded projects in the company, and there is no swap devices at all, no HDD etcs, just a CF card or flash memory card and swap is totally turned off. David Xu
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