Date: Tue, 27 Jul 2010 14:23:39 -0500 From: Andrew Gould <andrewlylegould@gmail.com> To: Debacker <debackerl@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: Real-Time Video Recording (ionice equivalent) Message-ID: <AANLkTinQx3Myo06ed7Q7Ou_r3tepGGYQFbfhYNJbpa6T@mail.gmail.com> In-Reply-To: <AANLkTinqwCSzoCdEnrSoXN1jkpoIGmESgbMsI3JFB5YF@mail.gmail.com> References: <AANLkTinqwCSzoCdEnrSoXN1jkpoIGmESgbMsI3JFB5YF@mail.gmail.com>
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On Tue, Jul 27, 2010 at 1:45 PM, Debacker <debackerl@gmail.com> wrote: > Hi, > > I'm looking for a ionice equivalent for FreeBSD. Let suppose that I setup a > NAS using FreeBSD. I can substain 50MiB/s writing. > Let suppose that I have a 720p security camera, writing at 2 MiB/s in a > file. Then I have 10 users copying files around. > All of this activity (camera + users) through Samba, so each connection has > a dedicated process. > > Problem is that I want to give camera's maximal priority to guarantee smooth > recording. > > I don't expect Samba to use much CPU, 99% should be spent in IO. So if I set > the nice value of camera's process to Real-Time, it should do much, because > its process will be on wait status most of the time. > Consequently, when some IO requests coming from camera's process are in the > queue, I want them to have top priority compared to requests coming from > other processes. > As the camera is limited to 2MiB/s, I expect the system to remain > responsive. > > I know that seeks may lower the speed of the HDD, but as the HDD is slowing > down, completing requests, I expect the number of camera IO requests to > increase in the queue, and to be packed together, hopefully, stabilizing the > number of seeks. > > BTW, I would use "root preexec" setting of Samba to execute a shell script > for each new connection, giving best priority to the process if the user is > "camera". > > Any idea? > > Thanks > > Laurent Debacker Would putting the camera's storage space on a separate HDD from the other users help? Andrew
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