I figured this out with Bertl's help on IRC. Here's how to configure hard-cpu limits on Vserver devel branch to get all of your guests to share the CPU equally:
1) This requires the use of idle-time scheduling, which is supported in the devel-branch. Also, it turns out there was a subtle bug with idle-time scheduling that was fixed with a recent patch. So, you need the following kernel patches: patch-2.6.17.7-vs2.1.1-rc28.n.diff delta-sched-fix01.diff 2) When compiling the kernel be sure to enable the following vserver options: CONFIG_VSERVER_HARDCPU=y CONFIG_VSERVER_IDLETIME=y CONFIG_VSERVER_IDLELIMIT=y 3) The vserver-util userspace tools do not yet support configuring idle-time. So, you need to download and build the following tools: http://vserver.13thfloor.at/Experimental/TOOLS/vsched-0.03.tar.bz2 (required) http://vserver.13thfloor.at/Experimental/TOOLS/vcmd-0.03.tar.bz2 (optional -- can be used in place of vsched and for testing that idle time scheduling works) http://vserver.13thfloor.at/Experimental/TOOLS/cpuhog.c (optional -- for testing that idle time scheduling works) 4) Build vsched, vcmd, and cpuhog on the vserver host. 5) We will set the regular hard cpu rate/interval to an unrealistic value such as 1/1000 for all of the vserver guests. This will cause the guests to halt and their processes to go idle. We will configure a seperate "idle" bucket with idle_rate/idle_interval values of something reasonable like 50/100. With the idletime and idlelimit flags set in kernel config, instead of running the idle task, vserver will advance idle time and add tokens to the guests according to idle_rate/idle_interval. Of course, this assumes that the host server is idle, too. This will cause the guests to self-regulate their cpu usage and to share equally the cpu. This works in SMP systems, too. Note: if you have a busy host, idle time may not advance as expected. 6) Start some guests and have them run cpuhog (we use vcmd for testing here): vcmd -i 42 -BC ctx_create .flagword=^34^8 -- cpuhog & vcmd -i 43 -BC ctx_create .flagword=^34^8 -- cpuhog & vcmd -i 44 -BC ctx_create .flagword=^34^8 -- cpuhog & 8.) Run vsched to configure the cpu limits. We need to run it twice: once to configure regular rate/interval, set the idle time flag, and set the min and max bucket size; and another time to configure idle_rate/idle_interval: vsched -f -x <vserver_context_id> -u -1 -I 1000 -R 1 -M 50 -S 500 -i vsched -f -i -x <vserver_context_id> -u -1 -I 100 -R 50 the '-f' option overrides lazy-update and updates the cpu limit settings even if the guest is on hold. Also, note that the vserver needs to be running for vsched-0.03 to work. You can use a post-start script to automatically call vsched-0.03 whenever you start the guest. You cannot yet use /etc/vservers/<vserver-name>/schedule to set the idle-time flag, idle_rate, or idle_interval. 9) Watch idle time advance and monitor the scheduler to confirm that everything is working: watch -n 4 /proc/virtual/<xid>/sched You want to pay attention to the cpu<N> line(s). Here's what the values on each cpu<N> line represent: <user-ticks> <sys-ticks> <hold-ticks> <token-time> in ticks <idle-time> in ticks <H/R> on hold/running <I/-> idle time/normal <tokens> <tokens-min> <tokens-max> <fillrate>/<interval> <fillrate2>/<interval2> If <idle-time> is not advancing and your guests are on hold, run top and confirm that your host really is idle (x% id). -ekc On 8/9/06, EKC <[EMAIL PROTECTED]> wrote:
Hello, I am trying to figure out how to use the idle time feature in the devel branch and the vsched-0.02 tool. What I want to do is have P guests each use 1/P of host CPU time and to dynamically adjust to use 1/(P+Y) of CPU time when Y new guests are started. When guests are stopped, I want hard_sched to adjust accordingly for the remaining guests. I am using hard_sched now and I have to re-run vsched for every guest every time that I start a new guest. I understand (thank you Bertl for enlightening me on IRC) that the idle-time feature in the devel branch will take care of this for me. What's a simple example of how to use vsched0.02 (http://vserver.13thfloor.at/Experimental/TOOLS/vsched-0.02.tar.bz) to have P guests dynamically adjust to use 1/P of cpu time? Is the new vsched the best tool for this job? What would I need to do differently if I have more than 1 CPU? Thanks a lot! ekc
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