From nobody Tue Apr 7 01:57:31 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A866C433FE for ; Sun, 9 Oct 2022 09:08:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230166AbiJIJI3 (ORCPT ); Sun, 9 Oct 2022 05:08:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230094AbiJIJIB (ORCPT ); Sun, 9 Oct 2022 05:08:01 -0400 Received: from mail-pg1-x52a.google.com (mail-pg1-x52a.google.com [IPv6:2607:f8b0:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B37AB31DC8 for ; Sun, 9 Oct 2022 02:07:48 -0700 (PDT) Received: by mail-pg1-x52a.google.com with SMTP id 78so8052804pgb.13 for ; Sun, 09 Oct 2022 02:07:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Di6UYGr5o/GSN0ajTLtFClQB+xSRVwulRo8S0QrCcKI=; b=YhyVT+feaZTJaqgGyJt76SZs2ZcBpZEPkuaHpuvXaOtZOmphmqZgRaqvn3DYi0upEy t7yOIzNZs2gRP6fJS3kskvr4gH1ZoYrzP7/REgxqXRLm3i0Mufst4j2XcMHo7KeKIEop n/7EanSxuX44lUiLBTUef0T6xqzl8TmCaeIvc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Di6UYGr5o/GSN0ajTLtFClQB+xSRVwulRo8S0QrCcKI=; b=zZueOjiU3WBBsUhwKz850sMNxQB4E6ygp57xnajYLcvQ97j27eOptTQshOwO1U6J+k JthwWMlebvpLz48jBME6VqwjTOZOKR6TO8ea9vPZ05rykIFLm2Eb/ypdgnlHu8Fj2hvP iQEexzl9EUjr3DLBb6VGHWRDNLzBD7xPAHr/Io1qNFAbIVCvEm8XhdqbfTwlYGJjT+vU B8vZ3tSRPv0FQOIRhX8qY6r0P8TzXEMpSu47EHQFpYk9p7En4Ck2G8pqfe9xuWUi2jR4 KBXzwIp5ONV1Hix8sDdnkNZoTVpciN1qPSwwqTgkz6kpWXWS+RIVa1fv0JYWIxXfklNL 6KFw== X-Gm-Message-State: ACrzQf1ncO62xWe03szIhynqMNlaxNuvMw0LNDM4BAwLwLRVpG55MaeV 0j4bcdzsWrjZLCbf4sdPjx/aWIun0BFpUw== X-Google-Smtp-Source: AMsMyM7YWoa+daGBBBz9uSUN9qJ47XLGsV80REC7vAB/6UsA5DqmTTpqUmhteFDCgPBWGb9qrzm1Yw== X-Received: by 2002:a17:902:bd44:b0:17f:fc22:3a74 with SMTP id b4-20020a170902bd4400b0017ffc223a74mr11276401plx.161.1665306456519; Sun, 09 Oct 2022 02:07:36 -0700 (PDT) Received: from tigerii.tok.corp.google.com ([2401:fa00:8f:203:8517:d51e:5fe9:9be7]) by smtp.gmail.com with ESMTPSA id q194-20020a632acb000000b00439d071c110sm4335148pgq.43.2022.10.09.02.07.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 09 Oct 2022 02:07:36 -0700 (PDT) From: Sergey Senozhatsky To: Minchan Kim , Andrew Morton Cc: Nitin Gupta , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Sergey Senozhatsky Subject: [PATCHv3 4/8] zram: Introduce recompress sysfs knob Date: Sun, 9 Oct 2022 18:07:16 +0900 Message-Id: <20221009090720.1040633-5-senozhatsky@chromium.org> X-Mailer: git-send-email 2.38.0.rc1.362.ged0d419d3c-goog In-Reply-To: <20221009090720.1040633-1-senozhatsky@chromium.org> References: <20221009090720.1040633-1-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Allow zram to recompress (using secondary compression streams) pages. We support three modes: 1) IDLE pages recompression is activated by `idle` mode echo idle > /sys/block/zram0/recompress 2) Since there may be many idle pages user-space may pass a size watermark value and we will recompress IDLE pages only of equal or greater size: echo 888 > /sys/block/zram0/recompress 3) HUGE pages recompression is activated by `huge` mode echo huge > /sys/block/zram0/recompress 4) HUGE_IDLE pages recompression is activated by `huge_idle` mode echo huge_idle > /sys/block/zram0/recompress Signed-off-by: Sergey Senozhatsky --- drivers/block/zram/Kconfig | 12 +++ drivers/block/zram/zram_drv.c | 194 +++++++++++++++++++++++++++++++++- drivers/block/zram/zram_drv.h | 2 + 3 files changed, 205 insertions(+), 3 deletions(-) diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig index d4100b0c083e..7febf36e93eb 100644 --- a/drivers/block/zram/Kconfig +++ b/drivers/block/zram/Kconfig @@ -78,3 +78,15 @@ config ZRAM_MEMORY_TRACKING /sys/kernel/debug/zram/zramX/block_state. =20 See Documentation/admin-guide/blockdev/zram.rst for more information. + +config ZRAM_MULTI_COMP + bool "Enable multiple per-CPU compression streams" + depends on ZRAM + help + This will enable per-CPU multi-compression streams, so that ZRAM + can re-compress IDLE/huge pages, using a potentially slower but + more effective compression algorithm. Note, that IDLE page support + requires ZRAM_MEMORY_TRACKING. + + echo TIMEOUT > /sys/block/zramX/idle + echo SIZE > /sys/block/zramX/recompress diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 94c62d7ea818..12368e773f3d 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1282,6 +1282,12 @@ static void zram_free_page(struct zram *zram, size_t= index) atomic64_dec(&zram->stats.huge_pages); } =20 + if (zram_test_flag(zram, index, ZRAM_RECOMP)) + zram_clear_flag(zram, index, ZRAM_RECOMP); + + if (zram_test_flag(zram, index, ZRAM_RECOMP_SKIP)) + zram_clear_flag(zram, index, ZRAM_RECOMP_SKIP); + if (zram_test_flag(zram, index, ZRAM_WB)) { zram_clear_flag(zram, index, ZRAM_WB); free_block_bdev(zram, zram_get_element(zram, index)); @@ -1343,6 +1349,7 @@ static int zram_read_from_zspool(struct zram *zram, s= truct page *page, unsigned long handle; unsigned int size; void *src, *dst; + u32 idx; int ret; =20 handle =3D zram_get_handle(zram, index); @@ -1359,8 +1366,13 @@ static int zram_read_from_zspool(struct zram *zram, = struct page *page, =20 size =3D zram_get_obj_size(zram, index); =20 - if (size !=3D PAGE_SIZE) - zstrm =3D zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP]); + if (size !=3D PAGE_SIZE) { + idx =3D ZRAM_PRIMARY_ZCOMP; + if (zram_test_flag(zram, index, ZRAM_RECOMP)) + idx =3D ZRAM_SECONDARY_ZCOMP; + + zstrm =3D zcomp_stream_get(zram->comps[idx]); + } =20 src =3D zs_map_object(zram->mem_pool, handle, ZS_MM_RO); if (size =3D=3D PAGE_SIZE) { @@ -1372,7 +1384,7 @@ static int zram_read_from_zspool(struct zram *zram, s= truct page *page, dst =3D kmap_atomic(page); ret =3D zcomp_decompress(zstrm, src, size, dst); kunmap_atomic(dst); - zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]); + zcomp_stream_put(zram->comps[idx]); } zs_unmap_object(zram->mem_pool, handle); return ret; @@ -1603,6 +1615,180 @@ static int zram_bvec_write(struct zram *zram, struc= t bio_vec *bvec, return ret; } =20 +#ifdef CONFIG_ZRAM_MULTI_COMP +/* + * This function will decompress (unless it's ZRAM_HUGE) the page and then + * attempt to compress it using secondary compression algorithm (which is + * potentially more effective). + * + * Corresponding ZRAM slot should be locked. + */ +static int zram_recompress(struct zram *zram, + u32 index, + struct page *page, + int size_watermark) +{ + unsigned long handle_prev; + unsigned long handle_next; + unsigned int comp_len_next; + unsigned int comp_len_prev; + struct zcomp_strm *zstrm; + void *src, *dst; + int ret; + + handle_prev =3D zram_get_handle(zram, index); + if (!handle_prev) + return -EINVAL; + + comp_len_prev =3D zram_get_obj_size(zram, index); + /* + * Do not recompress objects that are already "small enough". + */ + if (comp_len_prev < size_watermark) + return 0; + + ret =3D zram_read_from_zspool(zram, page, index); + if (ret) + return ret; + + zstrm =3D zcomp_stream_get(zram->comps[ZRAM_SECONDARY_ZCOMP]); + src =3D kmap_atomic(page); + ret =3D zcomp_compress(zstrm, src, &comp_len_next); + kunmap_atomic(src); + + /* + * Either a compression error or we failed to compressed the object + * in a way that will save us memory. Mark the object so that we + * don't attemp to re-compress it again (RECOMP_SKIP). + */ + if (comp_len_next >=3D huge_class_size || + comp_len_next >=3D comp_len_prev || + ret) { + zram_set_flag(zram, index, ZRAM_RECOMP_SKIP); + zram_clear_flag(zram, index, ZRAM_IDLE); + zcomp_stream_put(zram->comps[ZRAM_SECONDARY_ZCOMP]); + return ret; + } + + /* + * No direct reclaim (slow path) for handle allocation and no + * re-compression attempt (unlike in __zram_bvec_write()) since + * we already stored that object in zsmalloc. If we cannot alloc + * memory then me bail out. + */ + handle_next =3D zs_malloc(zram->mem_pool, comp_len_next, + __GFP_KSWAPD_RECLAIM | + __GFP_NOWARN | + __GFP_HIGHMEM | + __GFP_MOVABLE); + if (IS_ERR((void *)handle_next)) { + zcomp_stream_put(zram->comps[ZRAM_SECONDARY_ZCOMP]); + return -ENOMEM; + } + + dst =3D zs_map_object(zram->mem_pool, handle_next, ZS_MM_WO); + memcpy(dst, zstrm->buffer, comp_len_next); + zcomp_stream_put(zram->comps[ZRAM_SECONDARY_ZCOMP]); + + zs_unmap_object(zram->mem_pool, handle_next); + + zram_free_page(zram, index); + zram_set_handle(zram, index, handle_next); + zram_set_obj_size(zram, index, comp_len_next); + + zram_set_flag(zram, index, ZRAM_RECOMP); + atomic64_add(comp_len_next, &zram->stats.compr_data_size); + atomic64_inc(&zram->stats.pages_stored); + + return 0; +} + +#define RECOMPRESS_IDLE (1 << 0) +#define RECOMPRESS_HUGE (1 << 1) + +static ssize_t recompress_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t len) +{ + struct zram *zram =3D dev_to_zram(dev); + unsigned long nr_pages =3D zram->disksize >> PAGE_SHIFT; + unsigned long index; + struct page *page; + ssize_t ret =3D 0; + int mode, size_watermark =3D 0; + + if (sysfs_streq(buf, "idle")) { + mode =3D RECOMPRESS_IDLE; + } else if (sysfs_streq(buf, "huge")) { + mode =3D RECOMPRESS_HUGE; + } else if (sysfs_streq(buf, "huge_idle")) { + mode =3D RECOMPRESS_IDLE | RECOMPRESS_HUGE; + } else { + /* + * We will re-compress only idle objects equal or greater + * in size than watermark. + */ + ret =3D kstrtoint(buf, 10, &size_watermark); + if (ret) + return ret; + mode =3D RECOMPRESS_IDLE; + } + + if (size_watermark > PAGE_SIZE) + return ret; + + down_read(&zram->init_lock); + if (!init_done(zram)) { + ret =3D -EINVAL; + goto release_init_lock; + } + + page =3D alloc_page(GFP_KERNEL); + if (!page) { + ret =3D -ENOMEM; + goto release_init_lock; + } + + for (index =3D 0; index < nr_pages; index++) { + zram_slot_lock(zram, index); + + if (!zram_allocated(zram, index)) + goto next; + + if (mode & RECOMPRESS_IDLE && + !zram_test_flag(zram, index, ZRAM_IDLE)) + goto next; + + if (mode & RECOMPRESS_HUGE && + !zram_test_flag(zram, index, ZRAM_HUGE)) + goto next; + + if (zram_test_flag(zram, index, ZRAM_WB) || + zram_test_flag(zram, index, ZRAM_UNDER_WB) || + zram_test_flag(zram, index, ZRAM_SAME) || + zram_test_flag(zram, index, ZRAM_RECOMP) || + zram_test_flag(zram, index, ZRAM_RECOMP_SKIP)) + goto next; + + ret =3D zram_recompress(zram, index, page, size_watermark); +next: + zram_slot_unlock(zram, index); + if (ret) + break; + + cond_resched(); + } + + ret =3D len; + __free_page(page); + +release_init_lock: + up_read(&zram->init_lock); + return ret; +} +#endif + /* * zram_bio_discard - handler on discard request * @index: physical block index in PAGE_SIZE units @@ -1983,6 +2169,7 @@ static DEVICE_ATTR_RW(writeback_limit_enable); #endif #ifdef CONFIG_ZRAM_MULTI_COMP static DEVICE_ATTR_RW(recomp_algorithm); +static DEVICE_ATTR_WO(recompress); #endif =20 static struct attribute *zram_disk_attrs[] =3D { @@ -2009,6 +2196,7 @@ static struct attribute *zram_disk_attrs[] =3D { &dev_attr_debug_stat.attr, #ifdef CONFIG_ZRAM_MULTI_COMP &dev_attr_recomp_algorithm.attr, + &dev_attr_recompress.attr, #endif NULL, }; diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 4044ddbb2326..09b9ceb5dfa3 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -49,6 +49,8 @@ enum zram_pageflags { ZRAM_UNDER_WB, /* page is under writeback */ ZRAM_HUGE, /* Incompressible page */ ZRAM_IDLE, /* not accessed page since last idle marking */ + ZRAM_RECOMP, /* page was recompressed */ + ZRAM_RECOMP_SKIP, /* secondary algorithm cannot compress this page */ =20 __NR_ZRAM_PAGEFLAGS, }; --=20 2.38.0.rc1.362.ged0d419d3c-goog