Date: Fri, 27 Jun 2003 04:39:10 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: "D. J. Bernstein" <djb@cr.yp.to> Cc: freebsd-performance@freebsd.org Subject: Re: ten thousand small processes Message-ID: <3EFC2CDE.8AE25B2C@mindspring.com> References: <20030626025029.71392.qmail@cr.yp.to> <20030626212659.51367.qmail@cr.yp.to>
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"D. J. Bernstein" wrote: > Bakul Shah writes: > > Instead of complaining about wasting 78 megabytes and arguing > > about why various proposed solutions fall short and why your > > way is the best, why don't you come up with a patch that > > saves space for small programs? > > Funny. Seems to me that I keep making concrete suggestions---including a > detailed proposal for giving more space to malloc()---and the answer is > consistently ``We really don't care about per-process overhead.'' What's > the benefit of a patch for people who don't even see the problem? Your "concrete proposal for malloc" made a number of bad assumptions: o "UVA == 4G", rather than "UVA + KVA == 4G" Costs to move to "UVA == 4G": o pages must be mapped before each copy of data across a protection domain o pages must be unmapped afterwards o If we had access to another 2G of UVA, we'd have no better use for it than to make malloc more space efficient My answer, at least, was "too computationally expensive for a general purpose OS when making the size/computational overhead tradeoff". -- Terry
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