On Tue, May 10, 2011 at 4:48 PM, Lukas Czerner <lczerner@xxxxxxxxxx> wrote: > On Thu, 24 Mar 2011, amir73il@xxxxxxxxxxxxxxxxxxxxx wrote: > >> The purpose of this patch set is the removal of grp->alloc_sem locks >> from block allocation paths. >> >> The resulting code is cleaner and should perform better in concurrent >> allocating tasks workloads. > Hi Amir, > > Do you have any performance numbers indicating performance improvement > in concurrent allocations ? The only point where I can see taking > write semaphore is in filesystem resize code. Or am I missing something ? Yes, you are. down_write is also taken when initializing a block group buddy cache for the first time (NEED_INIT flag is set). Anyway, I do NOT have any performance number since this wasn't the purpose of this work. This work was done for snapshots, but I do think that as I wrote: 1. The resulting code is cleaner 2. Getting rid of an unneeded semaphore in allocation path can only do good to performance, but I certainly don't have the kind of high scalability testing setup to show the performance improvements if there are any. > > Thanks! > -Lukas > >> >> I ran several xfstests runs with these patches (4K and 1K block size). >> I tried several online resizes and verifyed that both in-core and on-disk >> group counters are correct. >> >> v2->v1: >> - fix silly bug in patch 4/5 that triggers BUG_ON(incore == NULL) >> - replace get_undo_access() with get_write_access() >> - ran xfstests with block size 1K (where 2 groups share a buddy page) >> >> [PATCH v2 1/5] ext4: move ext4_add_groupblocks() to mballoc.c >> [PATCH v2 2/5] ext4: implement ext4_add_groupblocks() by freeing blocks >> [PATCH v2 3/5] ext4: synchronize ext4_mb_init_group() with buddy page lock >> [PATCH v2 4/5] ext4: teach ext4_mb_init_cache() to skip uptodate buddy caches >> [PATCH v2 5/5] ext4: remove alloc_semp >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > -- > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
