From nobody Wed Oct 8 00:56:21 2025 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2D56225CC5D; Fri, 4 Jul 2025 04:23:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.17 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751603028; cv=none; b=Wo4tkCo09Nu9qls4UE7k8xtujp/dsWD3Z3QLKedVQxwRs5sc/n5yPNn5EdFsvuxpC5w98B06tQuC6dbsWs1Oz6i7VinMy3e9hYo5soaeXShJtGkQXHLEkj0SS7YrUd5MHwxvB9Kzn2Xfxkn1501fBDRtc5syz7qZZXlO1eivxZ0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751603028; c=relaxed/simple; bh=dsmrNIrsQRitZVBWm1T/+yLHRgRb6apZYbrIg0NfnHI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=r0fClo3HhB9udNThoMfRg77U64ADd1+Iw3/nCZdJttrr3+kUet2pf+f2m8HCH8l0OgStWbSPdZAedpYQ61tduxi6NKJjAvhqFqY/4j1ETwhSWJ3KtYFh/jzRn3dCwUlp4viBTitNV+IOSTYq7cteCJh289hzuWBnaSgwX1GT5NY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=YYD9H6+D; arc=none smtp.client-ip=198.175.65.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="YYD9H6+D" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1751603026; x=1783139026; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=dsmrNIrsQRitZVBWm1T/+yLHRgRb6apZYbrIg0NfnHI=; b=YYD9H6+DObHnzKehOdfko9/vplvpu2Tzlsr44+Yk/luFrjUugoX8kKXH t74oDTgd63dVx3d2URkpwRyd0IpwRH2cbkEYu0sPB8nCqtnPVvlw00Se6 LeXvLTUuGeKjMIA/fbLqt/7Obo3lUTQkHv82fnr3R35NFtabi8cxSwi7a RLp+ohKP04KZv252+GY0P9+9TwUYGipLwGmevh0neolUpYwyqtwrxegst FV83TpRnJJZNEXEqONEJTNkdBLvi0thSoxrUlNFykz2Dy1Wmp0X+zbGyv I2tkqoSz4yqEhidiL0bbcn9RJiT6fv9zVk6L5CkBKtPxd0jdXAU9SYYG8 w==; X-CSE-ConnectionGUID: 4NW96/JvSkCD4dF3Jhr20A== X-CSE-MsgGUID: pCQWDIotQ7KT24XvQ6uWlg== X-IronPort-AV: E=McAfee;i="6800,10657,11483"; a="53909252" X-IronPort-AV: E=Sophos;i="6.16,286,1744095600"; d="scan'208";a="53909252" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by orvoesa109.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jul 2025 21:23:28 -0700 X-CSE-ConnectionGUID: tkAhT05GQ0aE9AEbvr8Qlg== X-CSE-MsgGUID: TcTziTUUStqbmaiVEpJTDQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,286,1744095600"; d="scan'208";a="153968731" Received: from jf5300-b11a338t.jf.intel.com ([10.242.51.115]) by orviesa006.jf.intel.com with ESMTP; 03 Jul 2025 21:23:27 -0700 From: Kanchana P Sridhar To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, hannes@cmpxchg.org, yosry.ahmed@linux.dev, nphamcs@gmail.com, chengming.zhou@linux.dev, usamaarif642@gmail.com, ryan.roberts@arm.com, 21cnbao@gmail.com, ying.huang@linux.alibaba.com, akpm@linux-foundation.org, senozhatsky@chromium.org, linux-crypto@vger.kernel.org, herbert@gondor.apana.org.au, davem@davemloft.net, clabbe@baylibre.com, ardb@kernel.org, ebiggers@google.com, surenb@google.com, kristen.c.accardi@intel.com, vinicius.gomes@intel.com Cc: wajdi.k.feghali@intel.com, vinodh.gopal@intel.com, kanchana.p.sridhar@intel.com Subject: [PATCH v10 23/25] mm: zswap: Allocate pool batching resources if the compressor supports batching. Date: Thu, 3 Jul 2025 21:23:21 -0700 Message-Id: <20250704042323.10318-24-kanchana.p.sridhar@intel.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20250704042323.10318-1-kanchana.p.sridhar@intel.com> References: <20250704042323.10318-1-kanchana.p.sridhar@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This patch sets up zswap for allocating per-CPU resources optimally for non-batching and batching compressors. A new ZSWAP_MAX_BATCH_SIZE constant is defined as 8U, to set an upper limit on the number of pages in large folios that will be batch compressed. As per Herbert's comments in [2] in response to the crypto_acomp_batch_compress() and crypto_acomp_batch_decompress() API proposed in [1], this series does not create new crypto_acomp batching API. Instead, zswap compression batching uses the existing crypto_acomp_compress() API in combination with the "void *kernel_data" member added to "struct acomp_req" earlier in this series. It is up to the compressor to manage multiple requests, as needed, to accomplish batch parallelism. zswap only needs to allocate the per-CPU dst buffers according to the batch size supported by the compressor. A "u8 compr_batch_size" member is added to "struct zswap_pool", as per Yosry's suggestion. pool->compr_batch_size is set as the minimum of the compressor's max batch-size and ZSWAP_MAX_BATCH_SIZE. Accordingly, it proceeds to allocate the necessary compression dst buffers in the per-CPU acomp_ctx. Another "u8 batch_size" member is added to "struct zswap_pool" to store the unit for batching large folio stores: for batching compressors, this is the pool->compr_batch_size. For non-batching compressors, this is ZSWAP_MAX_BATCH_SIZE/4. zswap does not use more than one dst buffer yet. Follow-up patches will actually utilize the multiple acomp_ctx buffers for batch compression/decompression of multiple pages. Thus, ZSWAP_MAX_BATCH_SIZE limits the amount of extra memory used for batching. There is a small extra memory overhead of allocating the acomp_ctx->buffers array for compressors that do not support batching: On x86_64, the overhead is 1 pointer per-CPU (i.e. 8 bytes). [1]: https://patchwork.kernel.org/project/linux-mm/patch/20250508194134.283= 92-11-kanchana.p.sridhar@intel.com/ [2]: https://patchwork.kernel.org/comment/26382610 Signed-off-by: Kanchana P Sridhar --- mm/zswap.c | 82 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 63 insertions(+), 19 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index 688ce7ed39ca8..d4e4475ba5c5d 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -80,6 +80,9 @@ static bool zswap_pool_reached_full; =20 #define ZSWAP_PARAM_UNSET "" =20 +/* Limit the batch size to limit per-CPU memory usage for dst buffers. */ +#define ZSWAP_MAX_BATCH_SIZE 8U + static int zswap_setup(void); =20 /* Enable/disable zswap */ @@ -147,7 +150,7 @@ struct crypto_acomp_ctx { struct crypto_acomp *acomp; struct acomp_req *req; struct crypto_wait wait; - u8 *buffer; + u8 **buffers; struct mutex mutex; bool is_sleepable; }; @@ -166,6 +169,8 @@ struct zswap_pool { struct work_struct release_work; struct hlist_node node; char tfm_name[CRYPTO_MAX_ALG_NAME]; + u8 compr_batch_size; + u8 batch_size; }; =20 /* Global LRU lists shared by all zswap pools. */ @@ -258,8 +263,10 @@ static void __zswap_pool_empty(struct percpu_ref *ref); * zswap_cpu_comp_prepare(), not others. * - Cleanup acomp_ctx resources on all cores in zswap_pool_destroy(). */ -static void acomp_ctx_dealloc(struct crypto_acomp_ctx *acomp_ctx) +static void acomp_ctx_dealloc(struct crypto_acomp_ctx *acomp_ctx, u8 nr_bu= ffers) { + u8 i; + if (IS_ERR_OR_NULL(acomp_ctx)) return; =20 @@ -269,7 +276,11 @@ static void acomp_ctx_dealloc(struct crypto_acomp_ctx = *acomp_ctx) if (!IS_ERR_OR_NULL(acomp_ctx->acomp)) crypto_free_acomp(acomp_ctx->acomp); =20 - kfree(acomp_ctx->buffer); + if (acomp_ctx->buffers) { + for (i =3D 0; i < nr_buffers; ++i) + kfree(acomp_ctx->buffers[i]); + kfree(acomp_ctx->buffers); + } } =20 static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *nod= e) @@ -277,6 +288,7 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, str= uct hlist_node *node) struct zswap_pool *pool =3D hlist_entry(node, struct zswap_pool, node); struct crypto_acomp_ctx *acomp_ctx =3D per_cpu_ptr(pool->acomp_ctx, cpu); int ret =3D -ENOMEM; + u8 i; =20 /* * The per-CPU pool->acomp_ctx is zero-initialized on allocation. @@ -289,10 +301,6 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, st= ruct hlist_node *node) if (!IS_ERR_OR_NULL(acomp_ctx->acomp)) return 0; =20 - acomp_ctx->buffer =3D kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node= (cpu)); - if (!acomp_ctx->buffer) - return ret; - acomp_ctx->acomp =3D crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to= _node(cpu)); if (IS_ERR_OR_NULL(acomp_ctx->acomp)) { pr_err("could not alloc crypto acomp %s : %ld\n", @@ -305,17 +313,36 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, s= truct hlist_node *node) acomp_ctx->req =3D acomp_request_alloc(acomp_ctx->acomp); if (IS_ERR_OR_NULL(acomp_ctx->req)) { pr_err("could not alloc crypto acomp_request %s\n", - pool->tfm_name); + pool->tfm_name); goto fail; } =20 - crypto_init_wait(&acomp_ctx->wait); + /* + * Allocate up to ZSWAP_MAX_BATCH_SIZE dst buffers if the + * compressor supports batching. + */ + pool->compr_batch_size =3D min(ZSWAP_MAX_BATCH_SIZE, + crypto_acomp_batch_size(acomp_ctx->acomp)); + + acomp_ctx->buffers =3D kcalloc_node(pool->compr_batch_size, sizeof(u8 *), + GFP_KERNEL, cpu_to_node(cpu)); + if (!acomp_ctx->buffers) + goto fail; + + for (i =3D 0; i < pool->compr_batch_size; ++i) { + acomp_ctx->buffers[i] =3D kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, + cpu_to_node(cpu)); + if (!acomp_ctx->buffers[i]) + goto fail; + } =20 /* * if the backend of acomp is async zip, crypto_req_done() will wakeup * crypto_wait_req(); if the backend of acomp is scomp, the callback * won't be called, crypto_wait_req() will return without blocking. */ + crypto_init_wait(&acomp_ctx->wait); + acomp_request_set_callback(acomp_ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG, crypto_req_done, &acomp_ctx->wait); =20 @@ -323,7 +350,7 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, str= uct hlist_node *node) return 0; =20 fail: - acomp_ctx_dealloc(acomp_ctx); + acomp_ctx_dealloc(acomp_ctx, pool->compr_batch_size); return ret; } =20 @@ -345,6 +372,7 @@ static struct zswap_pool *zswap_pool_create(char *type,= char *compressor) return NULL; } =20 + /* Many things rely on the zero-initialization. */ pool =3D kzalloc(sizeof(*pool), GFP_KERNEL); if (!pool) return NULL; @@ -407,13 +435,28 @@ static struct zswap_pool *zswap_pool_create(char *typ= e, char *compressor) goto ref_fail; INIT_LIST_HEAD(&pool->list); =20 + /* + * Set the unit of compress batching for large folios, for quick + * retrieval in the zswap_compress() fast path: + * If the compressor is sequential (@pool->compr_batch_size is 1), + * large folios will be compressed in batches of ZSWAP_MAX_BATCH_SIZE/4 + * pages, where each page in the batch is compressed sequentially. + * We see better performance by processing the folio in batches of + * ZSWAP_MAX_BATCH_SIZE/4, due to cache locality of working set + * structures. + */ + pool->batch_size =3D (pool->compr_batch_size > 1) ? + pool->compr_batch_size : ZSWAP_MAX_BATCH_SIZE/4; + zswap_pool_debug("created", pool); =20 return pool; =20 ref_fail: for_each_possible_cpu(cpu) - acomp_ctx_dealloc(per_cpu_ptr(pool->acomp_ctx, cpu)); + acomp_ctx_dealloc(per_cpu_ptr(pool->acomp_ctx, cpu), + pool->compr_batch_size); + error: if (pool->acomp_ctx) free_percpu(pool->acomp_ctx); @@ -472,7 +515,8 @@ static void zswap_pool_destroy(struct zswap_pool *pool) zswap_pool_debug("destroying", pool); =20 for_each_possible_cpu(cpu) - acomp_ctx_dealloc(per_cpu_ptr(pool->acomp_ctx, cpu)); + acomp_ctx_dealloc(per_cpu_ptr(pool->acomp_ctx, cpu), + pool->compr_batch_size); =20 free_percpu(pool->acomp_ctx); =20 @@ -942,7 +986,7 @@ static bool zswap_compress(struct page *page, struct zs= wap_entry *entry, =20 mutex_lock(&acomp_ctx->mutex); =20 - dst =3D acomp_ctx->buffer; + dst =3D acomp_ctx->buffers[0]; sg_init_table(&input, 1); sg_set_page(&input, page, PAGE_SIZE, 0); =20 @@ -1003,19 +1047,19 @@ static bool zswap_decompress(struct zswap_entry *en= try, struct folio *folio) =20 acomp_ctx =3D raw_cpu_ptr(entry->pool->acomp_ctx); mutex_lock(&acomp_ctx->mutex); - obj =3D zpool_obj_read_begin(zpool, entry->handle, acomp_ctx->buffer); + obj =3D zpool_obj_read_begin(zpool, entry->handle, acomp_ctx->buffers[0]); =20 /* * zpool_obj_read_begin() might return a kmap address of highmem when - * acomp_ctx->buffer is not used. However, sg_init_one() does not - * handle highmem addresses, so copy the object to acomp_ctx->buffer. + * acomp_ctx->buffers[0] is not used. However, sg_init_one() does not + * handle highmem addresses, so copy the object to acomp_ctx->buffers[0]. */ if (virt_addr_valid(obj)) { src =3D obj; } else { - WARN_ON_ONCE(obj =3D=3D acomp_ctx->buffer); - memcpy(acomp_ctx->buffer, obj, entry->length); - src =3D acomp_ctx->buffer; + WARN_ON_ONCE(obj =3D=3D acomp_ctx->buffers[0]); + memcpy(acomp_ctx->buffers[0], obj, entry->length); + src =3D acomp_ctx->buffers[0]; } =20 sg_init_one(&input, src, entry->length); --=20 2.27.0