Re: absurd I/O perf with ZFS: hangs on zfs-cv)
Eitan Adler li...@eitanadler.com wrote: On 17 January 2013 07:52, Fabian Keil freebsd-lis...@fabiankeil.de wrote: Eitan Adler li...@eitanadler.com wrote: I don't think there are any laptops with large amounts of RAM as far as ZFS is concerned. Haha okay: 8GB of RAM. It is taking me 45 minutes to make 5 commits to git. Something is wrong here but I have no idea what I should be looking at. Any ideas? Try sysutils/zfs-stats to get a rough idea of how ZFS is using the available memory. Anything in particular I should be looking for? I mainly look at the ARC Summary and the ARC Efficiency sections but I suppose all the information is useful in some situations. If you already followed tuning advice from the Internet without benchmarking it, try reverting it. I have done absolutely no tuning. Is there anything in particular I *should* tune? A common recommendation is to disable atime for all datasets where it isn't needed as it can cause lots of unnecessary write operations. With 8 GB of RAM ZFS enables prefetching by default and I assume for the git use case it's not too useful and could hurt performance by amplifying read operations. The Data Prefetch Efficiency is shown by zfs-stats and if it doesn't look too impressive you might want to disable prefetching to see if it helps. If your repository isn't fresh, you could also try git gc. My impression is that the automatic doesn't trigger frequently enough for larger repositories like /usr/src. Fabian signature.asc Description: PGP signature
Re: absurd I/O perf with ZFS: hangs on zfs-cv)
On 18 January 2013 05:20, Fabian Keil freebsd-lis...@fabiankeil.de wrote: A common recommendation is to disable atime for all datasets where it isn't needed as it can cause lots of unnecessary write operations. Good call. I thought I had already disabled atime updating but it turns out that some datasets had this property still on. With 8 GB of RAM ZFS enables prefetching by default and I assume for the git use case it's not too useful and could hurt performance by amplifying read operations. The Data Prefetch Efficiency is shown by zfs-stats and if it doesn't look too impressive you might want to disable prefetching to see if it helps. I will look at this number - thanks. If your repository isn't fresh, you could also try git gc. My impression is that the automatic doesn't trigger frequently enough for larger repositories like /usr/src. This isn't git specific. Doing anything remotely I/O related takes forever: - starting a new shell take over a minute - opening a file in vim which wasn't opened recently take a few minutes - etc. That said, I will be looking closely at the zfs-stats and see if I notice any patterns. -- Eitan Adler ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: absurd I/O perf with ZFS: hangs on zfs-cv)
On Tue, Jan 15, 2013 at 10:57 PM, Eitan Adler li...@eitanadler.com wrote: Hi all. Running FreeBSD 9.1-Release, I am seeing some absurd hangs (10 minutes or more to open a file) with SIGINFO informing me that the process is stuck on zio-io_cv. Does anyone have any suggestions for what I want to look at to tune this? https://wiki.freebsd.org/ZFSTuningGuide Even has a section on laptop settings. Also the ZFS Evil Tuning Guide -- Adam Vande More ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: absurd I/O perf with ZFS: hangs on zfs-cv)
On 17 January 2013 07:52, Fabian Keil freebsd-lis...@fabiankeil.de wrote: Eitan Adler li...@eitanadler.com wrote: I don't think there are any laptops with large amounts of RAM as far as ZFS is concerned. Haha okay: 8GB of RAM. It is taking me 45 minutes to make 5 commits to git. Something is wrong here but I have no idea what I should be looking at. Any ideas? Try sysutils/zfs-stats to get a rough idea of how ZFS is using the available memory. Anything in particular I should be looking for? If you already followed tuning advice from the Internet without benchmarking it, try reverting it. I have done absolutely no tuning. Is there anything in particular I *should* tune? Once you have gathered some more information it might make sense to ask again on freebsd-fs@. Ack. On a new system it's probably not an issue, but the recommendation is to keep around 20% of the pool free to keep the performance up. Good to know. I will be careful here. -- Eitan Adler ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: absurd I/O perf with ZFS: hangs on zfs-cv)
On 15 January 2013 23:57, Eitan Adler li...@eitanadler.com wrote: Hi all. Running FreeBSD 9.1-Release, I am seeing some absurd hangs (10 minutes or more to open a file) with SIGINFO informing me that the process is stuck on zio-io_cv. Does anyone have any suggestions for what I want to look at to tune this? This is on a newly bought laptop with large amounts of RAM and almost nothing else running. It is taking me 45 minutes to make 5 commits to git. Something is wrong here but I have no idea what I should be looking at. Any ideas? -- Eitan Adler ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
absurd I/O perf with ZFS: hangs on zfs-cv)
Hi all. Running FreeBSD 9.1-Release, I am seeing some absurd hangs (10 minutes or more to open a file) with SIGINFO informing me that the process is stuck on zio-io_cv. Does anyone have any suggestions for what I want to look at to tune this? This is on a newly bought laptop with large amounts of RAM and almost nothing else running. Please CC me as I am not subscribed. -- Eitan Adler ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
