From mboxrd@z Thu Jan 1 00:00:00 1970 From: Don Slutz Subject: Re: Strange interdependace between domains Date: Tue, 18 Feb 2014 12:58:45 -0500 Message-ID: <53039F55.3030901@terremark.com> References: <1646915994.20140213165604@gmail.com> <1392313015.32038.112.camel@Solace> <295276356.20140213222507@gmail.com> <6010385428.20140214120238@gmail.com> <1392398466.32038.334.camel@Solace> <752791084.20140217124616@gmail.com> <1392742549.32038.580.camel@Solace> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1392742549.32038.580.camel@Solace> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Dario Faggioli , Simon Martin Cc: Andrew Cooper , Ian Campbell , Nate Studer , Don Slutz , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 02/18/14 11:55, Dario Faggioli wrote: > On lun, 2014-02-17 at 12:46 +0000, Simon Martin wrote: >> Hyperthreading is just a way to improve CPU resource utilization. Even >> if you are doing a CPU intensive operation, a lot of the processor >> circuits are actually idle, so adding 2 pipelines to feed one >> processor is a good way to improve total throughput, but it does have >> it have it's caveats. I totally forgot this. >> >> Given the way that this works there isn't much that Xen can do. It is >> a physical restriction. >> > I know, and my point was not that we should try to "fix" in Xen, what's > impossible to fix, because it's just how hardware works... and that is > by design! > > I was only saying that there are cases, when you still need isolation, > but you can afford a bit more of uncertainty, there is the possibility > for Xen to at least try to do the right thing automagically. > > Basically, I'm ok with people looking for hard real-time response time > and jitter to have to pick up the proper hw platform, as a first step, > and properly fine tune it. For more _soft_ real-time workloads, I wish > we were (think we should be) able to do better, perhaps still with some > user required tweaks, but nothing equally intrusive, that's it. :-) I would thing that a warning message from the xl command(s) dealing with cpupool would help here. See below >> OK. This is my current configuration: >> >> Dom0 PCPU 0,1,2 no pinning >> win7x64 PCPU 1,2 pinned >> pv499 PCPU 3 pinned >> >> And I get the same interdependence. >> >> root@smartin-xen:~# xl list >> Name ID Mem VCPUs State Time(s) >> Domain-0 0 1253 3 r----- 37.1 >> win7x64 4 2046 2 ------ 106.8 >> pv499 5 128 1 r----- 66.8 >> root@smartin-xen:~# xl vcpu-list >> Name ID VCPU CPU State Time(s) CPU Affinity >> Domain-0 0 0 1 -b- 21.2 all >> Domain-0 0 1 2 r-- 8.8 all >> Domain-0 0 2 0 -b- 8.2 all >> win7x64 4 0 1 -b- 59.8 1 >> win7x64 4 1 2 -b- 49.0 2 >> pv499 5 0 3 r-- 70.2 3 >> root@smartin-xen:~# xl cpupool-list -c >> Name CPU list >> Pool-0 0,1,2 Change to something like: Pool-0 0,1,2 (and part of 3) >> pv499 3 Or add: Warning: cpupool's share hyperthreaded cpus. -Don Slutz >> I have gone back to my working settings. >> > Ok, thanks a lot for trying. I was hoping for that tweak, although > developed for completely different reasons, to be helpful in this case, > but it appears it is not. > > Probably, I wouldn't have pinned the two win7 vcpus either, but anyway, > I don't want to eat any more of your time... Glad you find a > configuration that is working out! :-) > > Thanks again and Regards, > Dario >