> -----Original Message----- > From: Barry Song <21cnbao@xxxxxxxxx> > Sent: Thursday, August 28, 2025 5:00 PM > To: Sridhar, Kanchana P <kanchana.p.sridhar@xxxxxxxxx> > Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; > hannes@xxxxxxxxxxx; yosry.ahmed@xxxxxxxxx; nphamcs@xxxxxxxxx; > chengming.zhou@xxxxxxxxx; usamaarif642@xxxxxxxxx; > ryan.roberts@xxxxxxx; ying.huang@xxxxxxxxxxxxxxxxx; akpm@linux- > foundation.org; senozhatsky@xxxxxxxxxxxx; linux-crypto@xxxxxxxxxxxxxxx; > herbert@xxxxxxxxxxxxxxxxxxx; davem@xxxxxxxxxxxxx; > clabbe@xxxxxxxxxxxx; ardb@xxxxxxxxxx; ebiggers@xxxxxxxxxx; > surenb@xxxxxxxxxx; Accardi, Kristen C <kristen.c.accardi@xxxxxxxxx>; > Gomes, Vinicius <vinicius.gomes@xxxxxxxxx>; Feghali, Wajdi K > <wajdi.k.feghali@xxxxxxxxx>; Gopal, Vinodh <vinodh.gopal@xxxxxxxxx> > Subject: Re: [PATCH v11 23/24] mm: zswap: zswap_store() will process a > large folio in batches. > > On Fri, Aug 1, 2025 at 4:36 PM Kanchana P Sridhar > <kanchana.p.sridhar@xxxxxxxxx> wrote: > > > > This patch modifies zswap_store() to store a batch of pages in large > > folios at a time, instead of storing one page at a time. It does this by > > calling a new procedure zswap_store_pages() with a range of > > "pool->batch_size" indices in the folio. > > > > zswap_store_pages() implements all the computes done earlier in > > zswap_store_page() for a single-page, for multiple pages in a folio, > > namely the "batch": > > > > 1) It starts by allocating all zswap entries required to store the > > batch. New procedures, zswap_entries_cache_alloc_batch() and > > zswap_entries_cache_free_batch() call kmem_cache_[free]alloc_bulk() > > to optimize the performance of this step. > > > > 2) Next, the entries fields are written, computes that need to be happen > > anyway, without modifying the zswap xarray/LRU publishing order. This > > improves latency by avoiding having the bring the entries into the > > cache for writing in different code blocks within this procedure. > > > > 3) Next, it calls zswap_compress() to sequentially compress each page in > > the batch. > > > > 4) Finally, it adds the batch's zswap entries to the xarray and LRU, > > charges zswap memory and increments zswap stats. > > > > 5) The error handling and cleanup required for all failure scenarios > > that can occur while storing a batch in zswap are consolidated to a > > single "store_pages_failed" label in zswap_store_pages(). Here again, > > we optimize performance by calling kmem_cache_free_bulk(). > > > > Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@xxxxxxxxx> > > --- > > mm/zswap.c | 218 ++++++++++++++++++++++++++++++++++++------------- > ---- > > 1 file changed, 149 insertions(+), 69 deletions(-) > > This seems fine overall. However, could we pull some data from the > cover letter. For example, even with hardware batching, we are still > improving performance. Since your cover letter is very long, readers > might fail to connect this data with the patches. Sure, will add the data in the commit log. Thanks, Kanchana > > Thanks > Barry
