Messages in this thread | | | Date | Mon, 14 Apr 2008 12:52:12 +0200 | From | Nadia Derbey <> | Subject | Re: [PATCH 00/13] Re: Scalability requirements for sysv ipc |
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Nadia Derbey wrote: > Peter Zijlstra wrote: > >> On Mon, 2008-04-14 at 07:18 +0200, Nadia Derbey wrote: >> >>> Peter Zijlstra wrote: >>> >>>> On Fri, 2008-04-11 at 18:17 +0200, Nadia.Derbey@bull.net wrote: >>>> >>>> >>>>> Here is finally the ipc ridr-based implementation I was talking >>>>> about last >>>>> week (see http://lkml.org/lkml/2008/4/4/208). >>>>> I couldn't avoid much of the code duplication, but at least made >>>>> things >>>>> incremental. >>>>> >>>>> Does somebody now a test suite that exists for the idr API, that I >>>>> could >>>>> run on this new api? >>>>> >>>>> Mike, can you try to run it on your victim: I had such a hard time >>>>> building >>>>> this patch, that I couldn't re-run the test on my 8-core with this new >>>>> version. So the last results I have are for 2.6.25-rc3-mm1. >>>>> >>>>> Also, I think a careful review should be done to avoid introducing >>>>> yet other >>>>> problems :-( >>>> >>>> >>>> >>>> Why duplicate the whole thing, when we converted the Radix tree to be >>>> RCU safe we did it in-place. Is there a reason this is not done for >>>> idr? >>>> >>>> >>>> >>> >>> I did that because I wanted to go fast and try to fix the performance >>> problem we have with sysV ipc's. I didn't want to introduce (yet >>> other) regressions in the code that uses idr's today and that works >>> well ;-) >>> May be in the future if this rcu based api appears to be ok, we can >>> replace one with the other? >> >> >> >>> From what I can see the API doesn't change at all, > > > Well, 1 interface changes, 1 is added and another one went away: > > 1) for the preload part (it becomes like the radix-tree preload part): > > int idr_pre_get(struct idr *, gfp_t); > would become > int idr_pre_get(gfp_t); > > 2) idr_pre_get_end() is added (same as radix_tree_preload_end()). > > 3) The idr_init() disappears. > > You might see that other interfaces are not provided by ridr, but this > is only because I've taken those that are useful for the ipc part (so > should not be a problem to make the whole thing rcu safe). > >> so I don't see why >> you need to duplicate - either the new code works as expected or its >> broken. > > > That's why I asked for an "IDR test suite": I wanted to test potential > regressions. > >> If it works its good enough for all IDR users, if its broken we >> should fix it. Seems simple enough.. am I missing something obvious? >> > > Regards, > Nadia >
BTW, I'm realizing that I forgot to send the results I've got - sorry for that (I finally could pass the pmsg/psem tests this morning):
These are the output files for the command:
for i in 1 2 3 4 5 6 7 8;do ./pmsg $i 5;done
pmsg_output.25_rc8_mm1.ref.8: output file for the 2.6.25-rc8-mm1 reference kernel pmsg_output.25_rc8_mm1.ridr.8: output file for the 2.6.25-rc8-mm1 refrence kernel, with ipc's using rcu-based idr's psem_output.25_rc8_mm1.ref.8: same as <1> for the psem test psem_output.25_rc8_mm1.ridr.8: same as <2> for the psem test
Regards, Nadia
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