Date: Thu, 25 Nov 2010 16:35:53 -0600 From: Adam Vande More <amvandemore@gmail.com> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: Kostik Belousov <kostikbel@gmail.com>, freebsd-stable@freebsd.org, Andriy Gapon <avg@freebsd.org> Subject: Re: top io mode Message-ID: <AANLkTin3-kut7bZyg9w3uo0Y-ocwmhKeptiPWVso=Oq6@mail.gmail.com> In-Reply-To: <20101125210449.GA57788@icarus.home.lan> References: <AANLkTikrKevf3x4nyi6=8Yz0BW=yZzf0W_Xa3XGQXy8N@mail.gmail.com> <4CEE88D9.4070200@DataIX.net> <AANLkTincWrdhq3my_RARtB17mneT77YZubQbFCN1Swzp@mail.gmail.com> <20101125200813.GA56066@icarus.home.lan> <AANLkTinVq8f6miLjqePEBOjN3CfhZJcPf%2B8njiKwTaL3@mail.gmail.com> <20101125205733.GA56845@icarus.home.lan> <20101125210449.GA57788@icarus.home.lan>
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On Thu, Nov 25, 2010 at 3:04 PM, Jeremy Chadwick <freebsd@jdc.parodius.com>wrote: > Bad form to follow up to my own Email of course, but some discussion > material: > I'm a frequent offender myself so I won't be pointing any fingers. "top -m io" doesn't show any I/O writes, while gstat(8) does, and to > numerous devices all which make up some form of ZFS pool. > Yes, it's a generic ZFS mirror. If you do something like "dd if=/dev/urandom of=/pool/file bs=64k", does > "top -m io" show write I/O for the "dd" process? > It does not on my ZFS STABLE system with Kostick's path. So the patch fixes reads, but not writes. cc'ing to notify in case he has more ideas. It does on my UFS CURRENT VM w/ out the patch. > If so, then possibly ZFS "internally" is doing something quietly/behind > the scenes (such as a disk flush or some sort of internal transaction > "thing"), thus the kernel would be responsible and not a process. > That was kind of my thought, and if that's the case there are two problems: 1. Can't identify what's responsible for IO. 2. Any money your company saves due to ZFS features is lost when you get the electric bill. /sarcasm So that said, how about "top -S -m io -U root" instead, which includes > system processes, since we can (probably) assume a non-root process > isn't responsible? > I should have mentioned I had already tried that (-HS) along with -o read/write to see what was happening, but no luck. Hopefully I don't get too confusing here because I'm going to contradict something I said earlier. The stats I posted from gstat are perhaps not directly related to the root issue. Similar stats to what I linked to from gstats can be seen in approx 10 - 15 intervals and is 0.0 %busy in between those updates. However the HD indicator light blinks in 1 second intervals constantly and this is what I want to track down. One more datapoint is that in single user mode, the blinking stops. sa(8) may suffer from the same affliction as a "dd if=/dev/zero of=/tmp/ delete.me bs=64k" had been running along with my constant blinking: galacticdominator# sa -m root 30 0.00cpu 0tio 1972k*sec adam 6 0.27cpu 0tio 2254k*sec Maybe it's some weird hardware issue, but there's at least one other FreeBSD user who is seeing similar behavior. -- Adam Vande More
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