Date: Thu, 23 Nov 2006 09:35:08 +0000 From: Dieter <freebsd@sopwith.solgatos.com> To: freebsd-questions@freebsd.org Subject: Re: processes not getting fair share of available disk I/O (was: Re: TCP parameters and interpreting tcpdump output ) Message-ID: <200611231735.RAA19097@sopwith.solgatos.com> In-Reply-To: Your message of "Thu, 23 Nov 2006 02:52:15 EST." <20061123075214.GA51991@xor.obsecurity.org>
next in thread | previous in thread | raw e-mail | index | archive | help
> > > > hw.ata.wc=3D3D0 > > > ^^^^^^^^^^^ > > > "Make my hard drive go reeeeally slow please (just in case I crash)" :) > >=20 > > Slower, yes, but not *that* slow. > >=20 > > Normal ls : 0.032 second. Two processes using same disk, multiply by two, > > so 0.064 second. Maybe the multiplier is more than 2, call it 10x, so > > 0.32 second. But I'm seeing a factor of over 9100x. > > Humour me and turn it back on, then see what happens. Where is the knob to turn the write cache on/off on a per-drive basis in FreeBSD? I can do this in NetBSD, but the only knob I can find in FreeBSD affects all drives, and requires a reboot. Humour me and read the Subject line. The ls does not get its fair share of disk I/O. Both times are with the disk's write cache in write-through mode. I'm not comparing times with the write cache in different modes. I'm comparing ls by itself against ls competing with cp.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200611231735.RAA19097>