Date: Wed, 19 Aug 1998 11:18:09 +0200 From: Wolfram Schneider <wosch@cs.tu-berlin.de> To: Terry Lambert <tlambert@primenet.com>, Marc Slemko <marcs@znep.com> Cc: hackers@FreeBSD.ORG Subject: Re: sendfile() API? Message-ID: <19980819111809.A22887@caramba.cs.tu-berlin.de> In-Reply-To: <199808171817.LAA06770@usr08.primenet.com>; from Terry Lambert on Mon, Aug 17, 1998 at 06:17:34PM %2B0000 References: <Pine.GSO.4.02A.9808162329430.26956-100000@redfish> <199808171817.LAA06770@usr08.primenet.com>
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On 1998-08-17 18:17:34 +0000, Terry Lambert wrote: > I have no doubt that it would be useful for static pages; I am just not > convinced that pushing the data over a call boundary is the real overhead > here. For an mmap'ed file, the only overhead is the copy from the VM > buffer to the mbuf. The only way such a call could eliminated this > overhead is by passing the VM buffers down as mbuf contents. This can > be done (I did the code for it on the VMS NetWare server), but it's > a lot of work. Who cares about data copy overhead? If the kernel spend 5% of the CPU time in copying, there are still 95% free CPU cycles. Freefall.freebsd.org transfers 20KB/s with a CPU load less than 0.01. http://www.freebsd.org/server-status Server uptime: 5 days 20 hours 26 minutes 44 seconds Total accesses: 1096361 - Total Traffic: 9.9 GB CPU Usage: u.859375 s.828125 cu1.96094 cs.304688 - .000782% CPU load 2.17 requests/sec - 20.6 kB/second - 9.5 kB/request -- Wolfram Schneider <wosch@freebsd.org> http://freebsd.org/~w/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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