On Fri, Mar 22, 2013 at 3:05 PM, Zach Brown <zab@xxxxxxxxxx> wrote: > On Fri, Mar 22, 2013 at 08:33:19PM +0200, Octavian Purdila wrote: >> When using a large number of threads performing AIO operations the >> IOCTX list may get a significant number of entries which will cause >> significant overhead. For example, when running this fio script: > > Indeed. But you also need to consider the impact this change has on the > typical case of only having one ctx in the mm. Please include > measurements of that case in the commit message. > Hi Zach, Good point, I will add those numbers. >> --- a/arch/s390/mm/pgtable.c >> +++ b/arch/s390/mm/pgtable.c >> @@ -831,7 +831,7 @@ int s390_enable_sie(void) >> task_lock(tsk); >> if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 || >> #ifdef CONFIG_AIO >> - !hlist_empty(&tsk->mm->ioctx_list) || >> + tsk->mm->ioctx_rtree.rnode || >> #endif > > Boy, what a curious thing. I wonder if this is still needed if we're no > longer storing the mm in the ctx after retry support is removed. > >> + err = radix_tree_insert(&mm->ioctx_rtree, ctx->user_id, ctx); > > Hmm. Is there anything stopping an exceptionally jerky app from racing > io_setup() and munmap() and having two contexts be mapped to the same > address and get the same user_id? I guess this would just return > -EEXIST, then, not do anything terrible. I guess that's OK? > Ah, interesting, didn't thought of that. But I guess it is OK to keep the WARN_ONCE there, as the application is not supposed to do the munmap. >> + idx, sizeof(ctx)/sizeof(void *)); > > ARRAY_SIZE(ctx) > > And why bother tracking the starting idx? If you're completely draining > it simply always start from 0? > I will fix these in the next version, thanks for reviewing ! -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
