On Tue, Dec 02, 2025 at 09:29:17AM +0000, Jon Hunter wrote: > > On 28/11/2025 11:37, Harry Yoo wrote: > > Currently, kvfree_rcu_barrier() flushes RCU sheaves across all slab > > caches when a cache is destroyed. This is unnecessary when destroying > > a slab cache; only the RCU sheaves belonging to the cache being destroyed > > need to be flushed. > > > > As suggested by Vlastimil Babka, introduce a weaker form of > > kvfree_rcu_barrier() that operates on a specific slab cache and call it > > on cache destruction. > > > > The performance benefit is evaluated on a 12 core 24 threads AMD Ryzen > > 5900X machine (1 socket), by loading slub_kunit module. > > > > Before: > > Total calls: 19 > > Average latency (us): 8529 > > Total time (us): 162069 > > > > After: > > Total calls: 19 > > Average latency (us): 3804 > > Total time (us): 72287 > > > > Link: > > https://lore.kernel.org/linux-mm/[email protected] > > Link: > > https://lore.kernel.org/linux-mm/[email protected] > > Link: > > https://lore.kernel.org/linux-mm/[email protected] > > Suggested-by: Vlastimil Babka <[email protected]> > > Signed-off-by: Harry Yoo <[email protected]> > > --- > > Thanks for the rapid fix. I have been testing this and can confirm that this > does fix the performance regression I was seeing.
Great! > BTW shouldn't we add a 'Fixes:' tag above? I would like to ensure that this > gets picked up for v6.18 stable. Good point, I added Cc: stable and Fixes: tags. (and your and Daniel's Reported-and-tested-by: tags) > Otherwise ... > > Tested-by: Jon Hunter <[email protected]> Thank you Jon and Daniel a lot for reporting regression and testing the fix! -- Cheers, Harry / Hyeonggon
