On Mon, Nov 30, 2015 at 11:00:35PM -0500, Waiman Long wrote: > I think the current kernel use power-of-2 kmemcaches to satisfy kalloc() > requests except when the size is less than or equal to 192 where there are > some non-power-of-2 kmemcaches available. Given that the task_group > structure is large enough with FAIR_GROUP_SCHED enabled, we shouldn't hit > the case that the allocated buffer is not cacheline aligned.
Using out-of-object storage is allowed (none of the existing sl*b allocators do so iirc). That is, its perfectly valid for a sl*b allocator for 64 byte objects to allocate 72 bytes for each object and use the 'spare' 8 bytes for object tracking or whatnot. That would respect the minimum alignment guarantee of 8 bytes but not provide the 'expected' object size alignment you're assuming. Also, we have the proper interfaces to request the explicit alignment for a reason. So if you need the alignment for correctness, use those. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
