Date: Tue, 13 Mar 2001 07:59:43 +0200 From: Mark Murray <mark@grondar.za> To: Matt Dillon <dillon@earth.backplane.com> Cc: "David Schwartz" <davids@webmaster.com>, current@FreeBSD.ORG Subject: Re: Ethernet entropy harvesting seriously pessimizes performance Message-ID: <200103130558.f2D5wnf94700@gratis.grondar.za> In-Reply-To: <200103122231.f2CMVaL75959@earth.backplane.com> ; from Matt Dillon <dillon@earth.backplane.com> "Mon, 12 Mar 2001 14:31:36 PST." References: <200103122231.f2CMVaL75959@earth.backplane.com>
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> Let me be clear about what I mean by interrupt rate limiting:
>
> interrupt()
> {
> harvester(...)
> }
It does that already.
> harvester(...)
> {
> if (queue is not full) {
> ... add data to queue (reasonably sized queue, like 32 entries)
> }
> }
It does that. I guess we differ on the idea of "reasonable".
> queue-runner(...)
> {
> for(;;) {
> sleep for 1/10 second
>
> Pull next item (if any) off queue
> }
> }
It almost does that, except it sleeps every N items where the user
is given control of N.
> That is what my patch does. If a high rate of interrupts occur, the
> queue becomes full almost instantly because the queue-runner only
> pulls one item off per 1/10 second. The result is that the
> harvester() routine effectively becomes a NOP for most of the
> interrupts.
My code does that. Do a "cat /dev/zero > /dev/random"
to see it in action.
M
--
Mark Murray
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