Date: Tue, 16 Nov 2010 14:11:28 +0100 From: Ollivier Robert <roberto@keltia.freenix.fr> To: freebsd-stable@freebsd.org Subject: Re: "High" cpu usage when using ZFS cache device Message-ID: <20101116131128.GB21229@rron.local> In-Reply-To: <AANLkTi=tJ-Hf%2BrMqG0=tEzNV2jJW-B_7Yu_ftW4tAMqT@mail.gmail.com> References: <AANLkTinzwyhABYxzWknzRFzLCbcDSd3BU2kQ5tX_SSk-@mail.gmail.com> <20101116003029.GC79816@numachi.com> <AANLkTinfTgXzf7t3PtO2VAef7NSkKWc0RnGdpv=6_-Vj@mail.gmail.com> <ibtqvp$bfq$1@dough.gmane.org> <AANLkTi=tJ-Hf%2BrMqG0=tEzNV2jJW-B_7Yu_ftW4tAMqT@mail.gmail.com>
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According to Christer Solskogen: > See, that is why I think it is a ZFS issue. Because I did that. > I created a UFS filesystem on the same usb stick. Mounted it and did a > "dd if=/dev/zero of=/mnt/file". > The systemload goes +0.6 instead if +10.3. Do not forget that everything that is read/written from/to USB devices goes through the CPU (no DMA or anything for USB devices). -- Ollivier ROBERT -=- FreeBSD: The Power to Serve! -=- roberto@keltia.net In memoriam to Ondine, our 2nd child: http://ondine.keltia.net/
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