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Tue, 23 Jun 2026 00:12:49 -0700 (PDT) Received: from pve-server ([49.205.216.49]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84564d6c25fsm10883733b3a.4.2026.06.23.00.12.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Jun 2026 00:12:49 -0700 (PDT) From: Ritesh Harjani (IBM) To: Barry Song Cc: linux-mm@kvack.org, Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Youngjun Park , David Hildenbrand , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Sayali Patil Subject: Re: [PATCH v4 3/3] powerpc: Kconfig: Enable THP_SWAP on Book3S64 In-Reply-To: Date: Tue, 23 Jun 2026 12:36:22 +0530 Message-ID: <1pdxybv5.ritesh.list@gmail.com> References: MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 120CB10000E X-Stat-Signature: 5b4wmxbi6u1jt31etthy4xcwzte3q7bm X-HE-Tag: 1782198770-838059 X-HE-Meta: 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 h19E0j0p 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Barry Song writes: > On Fri, Jun 19, 2026 at 12:41 PM Ritesh Harjani (IBM) > wrote: >> >> THP_SWAP avoids splitting of a transparent huge folio into 32 smaller >> 64K folios (Radix-64K pagesize / 2M PMD) or into 256 smaller 64K folios >> (Hash-64K pagesize / 16M PMD), during swapout. This improves the >> swapping performance since all the bookking & I/O submission happens >> once per large folio. More details at [1]. >> >> PowerPC Book3S64 could not enable this before because PMD_ORDER is >> selected at runtime depending upon the chosen MMU. The earlier patches >> in this series turn SWAPFILE_CLUSTER into a runtime value and introduce >> an ARCH_MAX_PMD_ORDER upperbound override for SWAP_NR_ORDERS. With those >> changes, we can now enable THP SWAP for Book3S64. >> >> This increases bandwidth throughput with zram backend for swapout by >> 40-50% with Radix and 100-130% with Hash (Tested by Sayali) > > Thanks! > > I am curious about the contents of the anonymous memory being tested > and the compression algorithm used by zram. > I am sure it was derived from your microbenchmark itself which you had shared here (so repetitive pattern) with default zram compression algorithm. Thanks for that :) https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d0637c505f I think I got your point - I can mention that it was a microbenchmark similar to yours and not a real world workload test. Is this what you meant here? -ritesh >> >> [1]: https://lore.kernel.org/all/20170515112522.32457-2-ying.huang@intel.com/ > > Best Regards > Barry