Hi All, To share with you all, this was picked as part of some review process. We looked for the details regarding the introduction of SLAB_MEM_SHARED(http://linux.derkeiler.com/Mailing-Lists/Kernel/2006-02/msg01409.html - provide the slab cache infrastructure to support cpuset memory spreading), and further the changes were introduced across all filesystems - http://lwn.net/Articles/173654/. Since, we do not have direct access to NUMA architecture machine, so could not think of verifying the changes - but looking at the respective changes - the changes in this patch does seems relevant keeping in sync with all changes. And, Yes David - these changes will make sense in case of CONFIG_SLAB. Please share your opinion on the above introductions irrespective of the code changes done in this patch. Thanks & Regards, Amit Sahrawat On Thu, Nov 17, 2011 at 3:22 AM, David Rientjes <rientjes@xxxxxxxxxx> wrote: > On Wed, 16 Nov 2011, Theodore Tso wrote: > >> On Nov 16, 2011, at 10:04 AM, Namjae Jeon wrote: >> >> > If slab caches set to SLAB_MEM_SPREAD flags, The allocation is spread >> > evenly over all the memory nodes instead of favoring allocation on the >> > node local to current cpu. >> >> And why do you think this is a good thing? For mballoc in particular, >> the data structures are used immediately and then freed immediately --- >> on the local node, so using a non-local memory just makes things worse >> in a NUMA system. >> > > I don't think this has the effect that Namjae thinks it does: this is only > useful for CONFIG_SLAB and when you have cpusets enabled with > cpuset.memory_spread_slab set. > > To test how useful it is, you should enable CONFIG_SLAB and then mount > cpusets, set cpuset.memory_spread_slab, and create an MPOL_INTERLEAVE > mempolicy over all online nodes. This will have the same effect as adding > SLAB_MEM_SPREAD to these slab caches (it just doesn't require the > mempolicy) and will be able to quantify the effects without any changes to > the kernel at all. > -- 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
