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SubjectRe: GGI Project Unhappy On Linux
Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> Moving some of the low level support doesn't change the stability per
> se, but it does give you more control over things and especially over
> abitration. The problem is there is a penalty for that. A syscall
> costs time and you have to really get the syscall count down to sane
> levels. A fast graphics card can plot a line in less time than a
> syscall takes, so it is a real hard issue

Er.. I've not been following this whole thread (not enough time), but
the kgi folks have had a solution for that one for quite a while:

declare a circular buffer somewhere in virtual memory that's large
enough for at least two physical pages (probably want more). Keep one
page unmapped and flush the mapped one(s) on segfault into buffer,
or on explicit flush request.

There's still a bit of a latency penalty, and of course you need to use
memory, but the syscall penalty is amortized over many requests.

--
Raul

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