Vivek Goyal wrote: > On Fri, Sep 11, 2009 at 03:16:23PM +0200, Jerome Marchand wrote: >> Vivek Goyal wrote: >>> On Thu, Sep 10, 2009 at 04:52:27PM -0400, Vivek Goyal wrote: >>>> On Thu, Sep 10, 2009 at 05:18:25PM +0200, Jerome Marchand wrote: >>>>> Vivek Goyal wrote: >>>>>> Hi All, >>>>>> >>>>>> Here is the V9 of the IO controller patches generated on top of >>>>>> 2.6.31-rc7. >>>>> >>>>> Hi Vivek, >>>>> >>>>> I've run some postgresql benchmarks for io-controller. Tests have been >>>>> made with 2.6.31-rc6 kernel, without io-controller patches (when >>>>> relevant) and with io-controller v8 and v9 patches. >>>>> I set up two instances of the TPC-H database, each running in their >>>>> own io-cgroup. I ran two clients to these databases and tested on each >>>>> that simple request: >>>>> $ select count(*) from LINEITEM; >>>>> where LINEITEM is the biggest table of TPC-H (6001215 entries, >>>>> 720MB). That request generates a steady stream of IOs. >>>>> >>>>> Time is measure by psql (\timing switched on). Each test is run twice >>>>> or more if there is any significant difference between the first two >>>>> runs. Before each run, the cache is flush: >>>>> $ echo 3 > /proc/sys/vm/drop_caches >>>>> >>>>> >>>>> Results with 2 groups of same io policy (BE) and same io weight (1000): >>>>> >>>>> w/o io-scheduler io-scheduler v8 io-scheduler v9 >>>>> first second first second first second >>>>> DB DB DB DB DB DB >>>>> >>>>> CFQ 48.4s 48.4s 48.2s 48.2s 48.1s 48.5s >>>>> Noop 138.0s 138.0s 48.3s 48.4s 48.5s 48.8s >>>>> AS 46.3s 47.0s 48.5s 48.7s 48.3s 48.5s >>>>> Deadl. 137.1s 137.1s 48.2s 48.3s 48.3s 48.5s >>>>> >>>>> As you can see, there is no significant difference for CFQ >>>>> scheduler. >>>> Thanks Jerome. >>>> >>>>> There is big improvement for noop and deadline schedulers >>>>> (why is that happening?). >>>> I think because now related IO is in a single queue and it gets to run >>>> for 100ms or so (like CFQ). So previously, IO from both the instances >>>> will go into a single queue which should lead to more seeks as requests >>>> from two groups will kind of get interleaved. >>>> >>>> With io controller, both groups have separate queues so requests from >>>> both the data based instances will not get interleaved (This almost >>>> becomes like CFQ where ther are separate queues for each io context >>>> and for sequential reader, one io context gets to run nicely for certain >>>> ms based on its priority). >>>> >>>>> The performance with anticipatory scheduler >>>>> is a bit lower (~4%). >>>>> >>> Hi Jerome, >>> >>> Can you also run the AS test with io controller patches and both the >>> database in root group (basically don't put them in to separate group). I >>> suspect that this regression might come from that fact that we now have >>> to switch between queues and in AS we wait for request to finish from >>> previous queue before next queue is scheduled in and probably that is >>> slowing down things a bit.., just a wild guess.. >>> >> Hi Vivek, >> >> I guess that's not the reason. I got 46.6s for both DB in root group with >> io-controller v9 patches. I also rerun the test with DB in different groups >> and found about the same result as above (48.3s and 48.6s). >> > > Hi Jerome, > > Ok, so when both the DB's are in root group (with io-controller V9 > patches), then you get 46.6 seconds time for both the DBs. That means there > is no regression in this case. In this case there is only one queue of > root group and AS is running timed read/write batches on this queue. > > But when both the DBs are put in separate groups then you get 48.3 and > 48.6 seconds respectively and we see regression. In this case there are > two queues belonging to each group. Elevator layer takes care of queue > group queue switch and AS runs timed read/write batches on these queues. > > If it is correct, then it does not exclude the possiblity that it is queue > switching overhead between groups?
Yes it's correct. I misunderstood you. Jerome > > Thanks > Vivek _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
