Date: Mon, 13 Nov 2006 21:38:21 +0000 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Luigi Rizzo <rizzo@icir.org> Cc: arch@freebsd.org Subject: Re: a proposed callout API Message-ID: <7327.1163453901@critter.freebsd.dk> In-Reply-To: Your message of "Mon, 13 Nov 2006 13:32:37 PST." <20061113133236.A28926@xorpc.icir.org>
next in thread | previous in thread | raw e-mail | index | archive | help
In message <20061113133236.A28926@xorpc.icir.org>, Luigi Rizzo writes: >On Mon, Nov 13, 2006 at 08:53:41PM +0000, Poul-Henning Kamp wrote: >> >i am a bit curious on why you want to split the callouts among >multiple data structures. A binary heap is optimal for the timeouts that will happen, but filling it up with timeouts that are unlikely to, and in most cases won't happen for a very long time will soak up CPU time used for pointlessly ordering the heap. Also, many of the "non-happening" timeouts are repeatedly rescheduled, the TCP keepalives for instance, having a data structure where this is free of cost is a big advantage. The other thing is that covering the entire range from hour long callouts to nanosecond callouts would require a 64 bit value or a tricky pseudo-FP encoding. By splitting them in two classes, I can use two different 31 bit encodings separated by the top bit. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?7327.1163453901>