Re: [CentOS] Control IO related to a process
Joseph L. Casale ha scritto: Is there a way to nice the IO on a process such as dd? If not, what could be a way to control the IO level of such a process from bogging down a server to severely. As I was told few days ago you cold nice the whole process, eg. nice 19 if=/xxx of=/xxx bs=nnn This should give all the other process priority over dd Hope this helps -- Regards Lorenzo Quatrini ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Control IO related to a process
Lorenzo Quatrini ha scritto: Joseph L. Casale ha scritto: Is there a way to nice the IO on a process such as dd? If not, what could be a way to control the IO level of such a process from bogging down a server to severely. As I was told few days ago you cold nice the whole process, eg. nice 19 if=/xxx of=/xxx bs=nnn Obviously there is a typo... nice 19 dd if=/xxx of=/xxx bs=nnn ^^ This should give all the other process priority over dd Hope this helps -- Regards Lorenzo Quatrini ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Control IO related to a process
On Tuesday 02 September 2008, Joseph L. Casale wrote: Is there a way to nice the IO on a process such as dd? If not, what could be a way to control the IO level of such a process from bogging down a server to severely. There is ionice (assuming CentOS-5) in the util-linux package. It's by no means perfect but unlike nice it atleast tries to do what you want :-) Try it out. /Peter signature.asc Description: This is a digitally signed message part. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Control IO related to a process
Lorenzo Quatrini wrote: Lorenzo Quatrini ha scritto: nice 19 dd if=/xxx of=/xxx bs=nnn ^^ probably - nice 19 dd if=/xxx of=/xxx bs=nnn + nice -n 19dd if=/xxx of=/xxx bs=nnn -- Best Wishes, PAIX-UANIC | SK3929-RIPE ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
RE: [CentOS] Control IO related to a process
nice doesn't really do anything with respect to I/O. Yes I tried it and it never made a diff from one end of the spectrum to the other:) The best way to control I/O in this manor is to physically isolate it from the rest of the system(be it on a different controller connected to different disks etc). Well, not always possible! I am going to try Peter's suggestion of ionice tonight. Thanks everyone! jlc ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Control IO related to a process
On Tue, 2008-09-02 at 16:28 +0200, Lorenzo Quatrini wrote: Joseph L. Casale ha scritto: Is there a way to nice the IO on a process such as dd? If not, what could be a way to control the IO level of such a process from bogging down a server to severely. As I was told few days ago you cold nice the whole process, eg. nice 19 if=/xxx of=/xxx bs=nnn This should give all the other process priority over dd Saw the type fix. Just want to mention that the bs= can have a substantial beneficial effect. By increasing the blocksize to a relative large value, the number of system and I/O calls is reduced. This *may* reduce the adverse effects that you see on overall system responsiveness. I often use 8192, 16384 and even 8Mb, a cylinder size. Give it a try. YMMV. Hope this helps -- Regards Lorenzo Quatrini snip sig stuff -- Bill ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
RE: [CentOS] Control IO related to a process
Peter Kjellstrom wrote: On Tuesday 02 September 2008, Joseph L. Casale wrote: Is there a way to nice the IO on a process such as dd? If not, what could be a way to control the IO level of such a process from bogging down a server to severely. There is ionice (assuming CentOS-5) in the util-linux package. It's by no means perfect but unlike nice it atleast tries to do what you want :-) If that doesn't do it for you then maybe choosing a different scheduler then cfq can help. Something like 'deadline' may work better for the workload. AFAIK ionice will only work with the cfq scheduler for now. -Ross __ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
RE: [CentOS] Control IO related to a process
If that doesn't do it for you then maybe choosing a different scheduler then cfq can help. Something like 'deadline' may work better for the workload. AFAIK ionice will only work with the cfq scheduler for now. Appreciate that info, I have just been reading about the difference but cant say I understand in real life what the difference between deadline versus cfq is. I will try changing it on the fly and running my tests. Thanks! jlc ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Control IO related to a process
On Tue, Sep 2, 2008 at 9:51 AM, Joseph L. Casale [EMAIL PROTECTED] wrote: Appreciate that info, I have just been reading about the difference but cant say I understand in real life what the difference between deadline versus cfq is. I will try changing it on the fly and running my tests. The CFQ elevator algorithm attempts to be fair to all i/o requests, without specific regard to performance. The deadline elevator is more aggressive in scheduling for minimal latency per device. For example, if you have one process that is doing more or less random i/o and another that is doing large block sequential i/o, the deadline elevator will pander to the latter whereas the cfq elevator will try to be fair in scheduling the i/os between the processes. Here's a decent, short write up on them: http://www.redhat.com/magazine/008jun05/features/schedulers/ HTH mhr ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Control IO related to a process
On Tue, 2 Sep 2008 10:21:31 -0700 MHR [EMAIL PROTECTED] wrote: On Tue, Sep 2, 2008 at 9:51 AM, Joseph L. Casale [EMAIL PROTECTED] wrote: Appreciate that info, I have just been reading about the difference but cant say I understand in real life what the difference between deadline versus cfq is. I will try changing it on the fly and running my tests. The CFQ elevator algorithm attempts to be fair to all i/o requests, without specific regard to performance. The deadline elevator is more aggressive in scheduling for minimal latency per device. For example, if you have one process that is doing more or less random i/o and another that is doing large block sequential i/o, the deadline elevator will pander to the latter whereas the cfq elevator will try to be fair in scheduling the i/os between the processes. Here's a decent, short write up on them: http://www.redhat.com/magazine/008jun05/features/schedulers/ HTH mhr ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos ionice? has nobidy mentioned this? -- Martyn Hare [EMAIL PROTECTED] pgpMoWUeXezzj.pgp Description: PGP signature ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
