Date: Fri, 17 Nov 2000 10:30:03 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: John Hay <jhay@icomtek.csir.co.za> Cc: arch@FreeBSD.org, (Mark Murray) <mark@grondar.za> Subject: Re: new monotime() call for all architectures. Message-ID: <XFMail.001117103003.jhb@FreeBSD.org> In-Reply-To: <200011171053.eAHArq488675@zibbi.icomtek.csir.co.za>
next in thread | previous in thread | raw e-mail | index | archive | help
On 17-Nov-00 John Hay wrote: >> >> I need a fast-as-possible "time" inside the kernel to help >> speed up the /dev/random device. I say "time", because although >> it needs to be a function of time (preferably accurate and linear), >> it has no need whatsoever to be "real time", so a simple counter >> is quite OK. >> >> Pentiums, Alphas and IA64's all have a suitable register on chip, >> while I have to make do with nanotime(9) on i386 and i486. >> >> I have prepared a monotime(9) call for the i386, alpha and ia64 >> architectures (patch enclosed). I have been running this for a >> week or two now with promising results (on a Pentium). With >> the exception of the minimum of "glue" (and nanotime on older >> architectures), these functions reduce to one instruction. >> > > Are you sure it will work on SMP machines? There is nothing that > synchronizes the onboard counters. Or will your code stay on one > cpu? It doesn't matter. He just needs a psuedo-timestamp for entropy gathering purposes. It dosen't need to be entirely precise, so if different CPU's counters are not 100% in sync it won't hurt anything. -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?XFMail.001117103003.jhb>