From owner-freebsd-questions Fri Aug 10 8:18:20 2001 Delivered-To: freebsd-questions@freebsd.org Received: from yonge.cs.toronto.edu (yonge.cs.toronto.edu [128.100.1.8]) by hub.freebsd.org (Postfix) with SMTP id 9FB7D37B406 for ; Fri, 10 Aug 2001 08:18:16 -0700 (PDT) (envelope-from khui@cs.toronto.edu) Received: from jane.cs.toronto.edu ([128.100.2.31]) by yonge.cs.toronto.edu with SMTP id <33977-21682>; Fri, 10 Aug 2001 11:18:09 -0400 Received: from gardiner.cs.toronto.edu by jane.cs.toronto.edu id <453140-21860>; Fri, 10 Aug 2001 11:17:59 -0400 Date: Fri, 10 Aug 2001 11:17:55 -0400 From: Kevin Hui X-Sender: khui@gardiner.cs To: Alfred Perlstein Cc: freebsd-questions@freebsd.org Subject: Re: Experiencing very slow raw write speeds on /dev/ad1 In-Reply-To: <20010810025156.N85642@elvis.mu.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG > > Adding write caching helped a lot. Now the write speed jumps to ~15.8MB/s > > instead of the previous 3.5MB/s. > > Are there any other such settings I should pay attention to? I asked > > because I believe that the performance is still not as good as can be. I > > have the rawio program running under Linux with the identical hardware > > (accessing the /dev/raw/raw0, which maps to /dev/hdb) and I got ~38.4MB/s > > raw write speed (BTW I get ~38.4MB/s from both Linux and FreeBSD when I do > > the single-process raw sequential read test). > > I'm a bit confused, where do the numbers differ and what are the numbers? The numbers from simple runs (standard chunk size, single I/O thread, sequential read and then sequential write) are provided below. The FreeBSD write number is less than half of what Linux is getting. -Kevin. Linux running rawio: -------------------- Linux# time ./rawio -p 1 -s 8000000000 -r -w /dev/raw/raw1 Random read Sequential read Random write Sequential write ID K/sec /sec K/sec /sec K/sec /sec K/sec /sec aw1 38406.8 2344 38656.5 2359 real 0m15.946s user 0m0.010s sys 0m1.790s FreeBSD running rawio: ---------------------- FreeBSD# time ./rawio -p 1 -s 8000000000 -r -w /dev/ad1 Random read Sequential read Random write Sequential write ID K/sec /sec K/sec /sec K/sec /sec K/sec /sec ad1 38410.4 2344 15732.6 960 26.06 real 0.00 user 1.18 sys To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message