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Message-ID: <20241001111045.GA1003400@cmpxchg.org> References: <20241001053222.6944-1-kanchana.p.sridhar@intel.com> <20241001053222.6944-7-kanchana.p.sridhar@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241001053222.6944-7-kanchana.p.sridhar@intel.com> X-Rspamd-Queue-Id: 73415C0008 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 5kmq5ec55gb3xom7xzmh4cmwejyferwe X-HE-Tag: 1727781052-978351 X-HE-Meta: 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 xZzz/VLK 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 30, 2024 at 10:32:21PM -0700, Kanchana P Sridhar wrote: > zswap_store() will store large folios by compressing them page by page. > > This patch provides a sequential implementation of storing a large folio > in zswap_store() by iterating through each page in the folio to compress > and store it in the zswap zpool. > > zswap_store() calls the newly added zswap_store_page() function for each > page in the folio. zswap_store_page() handles compressing and storing each > page. > > We check the global and per-cgroup limits once at the beginning of > zswap_store(), and only check that the limit is not reached yet. This is > racy and inaccurate, but it should be sufficient for now. We also obtain > initial references to the relevant objcg and pool to guarantee that > subsequent references can be acquired by zswap_store_page(). A new function > zswap_pool_get() is added to facilitate this. > > If these one-time checks pass, we compress the pages of the folio, while > maintaining a running count of compressed bytes for all the folio's pages. > If all pages are successfully compressed and stored, we do the cgroup > zswap charging with the total compressed bytes, and batch update the > zswap_stored_pages atomic/zswpout event stats with folio_nr_pages() once, > before returning from zswap_store(). > > If an error is encountered during the store of any page in the folio, > all pages in that folio currently stored in zswap will be invalidated. > Thus, a folio is either entirely stored in zswap, or entirely not stored > in zswap. > > The most important value provided by this patch is it enables swapping out > large folios to zswap without splitting them. Furthermore, it batches some > operations while doing so (cgroup charging, stats updates). > > This patch also forms the basis for building compress batching of pages in > a large folio in zswap_store() by compressing up to say, 8 pages of the > folio in parallel in hardware using the Intel In-Memory Analytics > Accelerator (Intel IAA). > > This change reuses and adapts the functionality in Ryan Roberts' RFC > patch [1]: > > "[RFC,v1] mm: zswap: Store large folios without splitting" > > [1] https://lore.kernel.org/linux-mm/20231019110543.3284654-1-ryan.roberts@arm.com/T/#u > > Co-developed-by: Ryan Roberts I would change that to Originally-by: Ryan Roberts > Signed-off-by: and drop this for now. > Signed-off-by: Kanchana P Sridhar Acked-by: Johannes Weiner