On 10/24/23 11:33, chengming.zhou@xxxxxxxxx wrote: > From: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx> > > Now we will freeze slabs when moving them out of node partial list to > cpu partial list, this method needs two cmpxchg_double operations: > > 1. freeze slab (acquire_slab()) under the node list_lock > 2. get_freelist() when pick used in ___slab_alloc() > > Actually we don't need to freeze when moving slabs out of node partial > list, we can delay freezing to when use slab freelist in ___slab_alloc(), > so we can save one cmpxchg_double(). > > And there are other good points: > - The moving of slabs between node partial list and cpu partial list > becomes simpler, since we don't need to freeze or unfreeze at all. > > - The node list_lock contention would be less, since we don't need to > freeze any slab under the node list_lock. > > We can achieve this because there is no concurrent path would manipulate > the partial slab list except the __slab_free() path, which is serialized > now. "which is now serialized by slab_test_node_partial() under the list_lock." ? > Since the slab returned by get_partial() interfaces is not frozen anymore > and no freelist in the partial_context, so we need to use the introduced ^ is returned in > freeze_slab() to freeze it and get its freelist. > > Similarly, the slabs on the CPU partial list are not frozen anymore, > we need to freeze_slab() on it before use. We can now delete acquire_slab() as it became unused. > Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx> With the fixup for CONFIG_SLUB_CPU_PARTIAL you mentioned, Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx> Also agreed with followup patch to rename unfreeze_partials(). Thanks!
