From owner-freebsd-questions Fri Feb 10 08:08:59 1995 Return-Path: questions-owner Received: (from root@localhost) by freefall.cdrom.com (8.6.9/8.6.6) id IAA23025 for questions-outgoing; Fri, 10 Feb 1995 08:08:59 -0800 Received: from cs.weber.edu (cs.weber.edu [137.190.16.16]) by freefall.cdrom.com (8.6.9/8.6.6) with SMTP id IAA23019 for ; Fri, 10 Feb 1995 08:08:58 -0800 Received: by cs.weber.edu (4.1/SMI-4.1.1) id AA11205; Fri, 10 Feb 95 09:02:55 MST From: terry@cs.weber.edu (Terry Lambert) Message-Id: <9502101602.AA11205@cs.weber.edu> Subject: Re: enet throughput To: wollman@halloran-eldar.lcs.mit.edu (Garrett Wollman) Date: Fri, 10 Feb 95 9:02:53 MST Cc: rminnich@mini.sarnoff.com, freebsd-questions@FreeBSD.org In-Reply-To: <9502100339.AA02532@halloran-eldar.lcs.mit.edu> from "Garrett Wollman" at Feb 9, 95 10:39:30 pm X-Mailer: ELM [version 2.4dev PL52] Sender: questions-owner@FreeBSD.org Precedence: bulk > Two almost identical Pentium 60's running yesterday's kernel, one with > a genuine SMC 8416 and one with a cheap 8216 clone: > > ttcp-r: 16777216 bytes in 16.56 real seconds = 989.23 KB/sec +++ > ttcp-r: 16777216 bytes in 2.89 CPU seconds = 5678.54 KB/cpu sec > ttcp-r: 11460 I/O calls, msec/call = 1.48, calls/sec = 691.93 > ttcp-r: 0.0user 2.8sys 0:16real 17% 52i+613d 138maxrss 0+2pf 6787+108csw > > ttcp-t: 16777216 bytes in 16.67 real seconds = 983.04 KB/sec +++ > ttcp-t: 16777216 bytes in 3.65 CPU seconds = 4494.08 KB/cpu sec > ttcp-t: 2048 I/O calls, msec/call = 8.33, calls/sec = 122.88 > ttcp-t: 0.0user 3.5sys 0:16real 21% 35i+440d 178maxrss 0+2pf 3969+41csw > > This on a moderately loaded (~ 100 machines) Ethernet. Hmmm... I think that ~5 times the number of I/O calls at ~1/6 the time per call is an interesting statistic. Seems to point right at the problem spots... minus one piece of discriminating information -- was this a UDP NFS problem or a TCP NFS problem? Latency hits hard (per packet) for request/response, and ttcp does not test for this, which yields one latency averaged across all packets. NFS writes which are not async are very nearly request/response because of the relative difference in time for window fill vs. doing a sync I/O to a disk. Terry Lambert terry@cs.weber.edu --- Any opinions in this posting are my own and not those of my present or previous employers.