From nobody Fri Sep 20 01:41:31 2024 Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (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 32D9018F2E8; Thu, 8 Aug 2024 12:43:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.190 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723120997; cv=none; b=WD7ogDtIUc4kfmyr3KQpY3B6jCEdemMzZwtyRgdcLrfk0v/cga2n/VjGHCx6whYycTaH31zicEULcGJGDvJlCikBFz/x8DWD3b7/rYRhIYXSgehKZME7YGgp2w5Ej1AGYZ2r9h89insDL/rR0Zs54EXWEOxXb1Xsj3+2t89DGx0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723120997; c=relaxed/simple; bh=Uz8yK71Ka0y/Z5Fhp2gHKeU0tMElHrqd1/m4B1F59aU=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TB2r5vxG/wRRyO8ieiWmiVyksxGn/Uuv5UpC/8o6i6NKn21YVvGQSNBMHQDLMRODxszp7Nd1XKYiqKKcHl6y5XgOkEdS4GHrIQZWNJ68su/GDBHDZ7y4843B4+4LOWnPOgLy0ZxFHfHiRMXZnV+KO3/fN2w/9NIrajSYz5tDg7I= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.190 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.163]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4Wfmn131Vwz20lCH; Thu, 8 Aug 2024 20:38:45 +0800 (CST) Received: from dggpemf200006.china.huawei.com (unknown [7.185.36.61]) by mail.maildlp.com (Postfix) with ESMTPS id DAA8E180018; Thu, 8 Aug 2024 20:43:12 +0800 (CST) Received: from localhost.localdomain (10.90.30.45) by dggpemf200006.china.huawei.com (7.185.36.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 8 Aug 2024 20:43:12 +0800 From: Yunsheng Lin To: , , CC: , , Yunsheng Lin , Alexander Duyck , Andrew Morton , Subject: [PATCH net-next v13 07/14] mm: page_frag: reuse existing space for 'size' and 'pfmemalloc' Date: Thu, 8 Aug 2024 20:37:07 +0800 Message-ID: <20240808123714.462740-8-linyunsheng@huawei.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20240808123714.462740-1-linyunsheng@huawei.com> References: <20240808123714.462740-1-linyunsheng@huawei.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 X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemf200006.china.huawei.com (7.185.36.61) Content-Type: text/plain; charset="utf-8" Currently there is one 'struct page_frag' for every 'struct sock' and 'struct task_struct', we are about to replace the 'struct page_frag' with 'struct page_frag_cache' for them. Before begin the replacing, we need to ensure the size of 'struct page_frag_cache' is not bigger than the size of 'struct page_frag', as there may be tens of thousands of 'struct sock' and 'struct task_struct' instances in the system. By or'ing the page order & pfmemalloc with lower bits of 'va' instead of using 'u16' or 'u32' for page size and 'u8' for pfmemalloc, we are able to avoid 3 or 5 bytes space waste. And page address & pfmemalloc & order is unchanged for the same page in the same 'page_frag_cache' instance, it makes sense to fit them together. After this patch, the size of 'struct page_frag_cache' should be the same as the size of 'struct page_frag'. CC: Alexander Duyck Signed-off-by: Yunsheng Lin --- include/linux/mm_types_task.h | 16 +++++----- include/linux/page_frag_cache.h | 52 +++++++++++++++++++++++++++++++-- mm/page_frag_cache.c | 49 +++++++++++++++++-------------- 3 files changed, 85 insertions(+), 32 deletions(-) diff --git a/include/linux/mm_types_task.h b/include/linux/mm_types_task.h index b1c54b2b9308..f2610112a642 100644 --- a/include/linux/mm_types_task.h +++ b/include/linux/mm_types_task.h @@ -50,18 +50,18 @@ struct page_frag { #define PAGE_FRAG_CACHE_MAX_SIZE __ALIGN_MASK(32768, ~PAGE_MASK) #define PAGE_FRAG_CACHE_MAX_ORDER get_order(PAGE_FRAG_CACHE_MAX_SIZE) struct page_frag_cache { - void *va; -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) + /* encoded_va consists of the virtual address, pfmemalloc bit and order + * of a page. + */ + unsigned long encoded_va; + +#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) && (BITS_PER_LONG <=3D 32) __u16 remaining; - __u16 size; + __u16 pagecnt_bias; #else __u32 remaining; + __u32 pagecnt_bias; #endif - /* we maintain a pagecount bias, so that we dont dirty cache line - * containing page->_refcount every time we allocate a fragment. - */ - unsigned int pagecnt_bias; - bool pfmemalloc; }; =20 /* Track pages that require TLB flushes */ diff --git a/include/linux/page_frag_cache.h b/include/linux/page_frag_cach= e.h index 7c9125a9aed3..4ce924eaf1b1 100644 --- a/include/linux/page_frag_cache.h +++ b/include/linux/page_frag_cache.h @@ -3,18 +3,66 @@ #ifndef _LINUX_PAGE_FRAG_CACHE_H #define _LINUX_PAGE_FRAG_CACHE_H =20 +#include +#include #include #include #include =20 +#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) +/* Use a full byte here to enable assembler optimization as the shift + * operation is usually expecting a byte. + */ +#define PAGE_FRAG_CACHE_ORDER_MASK GENMASK(7, 0) +#define PAGE_FRAG_CACHE_PFMEMALLOC_BIT BIT(8) +#define PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT 8 +#else +/* Compiler should be able to figure out we don't read things as any value + * ANDed with 0 is 0. + */ +#define PAGE_FRAG_CACHE_ORDER_MASK 0 +#define PAGE_FRAG_CACHE_PFMEMALLOC_BIT BIT(0) +#define PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT 0 +#endif + +static inline unsigned long encode_aligned_va(void *va, unsigned int order, + bool pfmemalloc) +{ + BUILD_BUG_ON(PAGE_FRAG_CACHE_MAX_ORDER > PAGE_FRAG_CACHE_ORDER_MASK); + BUILD_BUG_ON(PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT >=3D PAGE_SHIFT); + + return (unsigned long)va | (order & PAGE_FRAG_CACHE_ORDER_MASK) | + ((unsigned long)pfmemalloc << PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT); +} + +static inline unsigned long encoded_page_order(unsigned long encoded_va) +{ + return encoded_va & PAGE_FRAG_CACHE_ORDER_MASK; +} + +static inline bool encoded_page_pfmemalloc(unsigned long encoded_va) +{ + return !!(encoded_va & PAGE_FRAG_CACHE_PFMEMALLOC_BIT); +} + +static inline void *encoded_page_address(unsigned long encoded_va) +{ + return (void *)(encoded_va & PAGE_MASK); +} + static inline void page_frag_cache_init(struct page_frag_cache *nc) { - nc->va =3D NULL; + nc->encoded_va =3D 0; } =20 static inline bool page_frag_cache_is_pfmemalloc(struct page_frag_cache *n= c) { - return !!nc->pfmemalloc; + return encoded_page_pfmemalloc(nc->encoded_va); +} + +static inline unsigned int page_frag_cache_page_size(unsigned long encoded= _va) +{ + return PAGE_SIZE << encoded_page_order(encoded_va); } =20 void page_frag_cache_drain(struct page_frag_cache *nc); diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c index 70fb6dead624..2544b292375a 100644 --- a/mm/page_frag_cache.c +++ b/mm/page_frag_cache.c @@ -22,6 +22,7 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, gfp_t gfp_mask) { + unsigned long order =3D PAGE_FRAG_CACHE_MAX_ORDER; struct page *page =3D NULL; gfp_t gfp =3D gfp_mask; =20 @@ -30,23 +31,31 @@ static struct page *__page_frag_cache_refill(struct pag= e_frag_cache *nc, __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC; page =3D alloc_pages_node(NUMA_NO_NODE, gfp_mask, PAGE_FRAG_CACHE_MAX_ORDER); - nc->size =3D page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE; #endif - if (unlikely(!page)) + if (unlikely(!page)) { page =3D alloc_pages_node(NUMA_NO_NODE, gfp, 0); + if (unlikely(!page)) { + nc->encoded_va =3D 0; + return NULL; + } =20 - nc->va =3D page ? page_address(page) : NULL; + order =3D 0; + } + + nc->encoded_va =3D encode_aligned_va(page_address(page), order, + page_is_pfmemalloc(page)); =20 return page; } =20 void page_frag_cache_drain(struct page_frag_cache *nc) { - if (!nc->va) + if (!nc->encoded_va) return; =20 - __page_frag_cache_drain(virt_to_head_page(nc->va), nc->pagecnt_bias); - nc->va =3D NULL; + __page_frag_cache_drain(virt_to_head_page((void *)nc->encoded_va), + nc->pagecnt_bias); + nc->encoded_va =3D 0; } EXPORT_SYMBOL(page_frag_cache_drain); =20 @@ -63,33 +72,29 @@ void *__page_frag_alloc_va_align(struct page_frag_cache= *nc, unsigned int fragsz, gfp_t gfp_mask, unsigned int align_mask) { -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - unsigned int size =3D nc->size; -#else - unsigned int size =3D PAGE_SIZE; -#endif - unsigned int remaining; + unsigned long encoded_va =3D nc->encoded_va; + unsigned int size, remaining; struct page *page; =20 - if (unlikely(!nc->va)) { + if (unlikely(!encoded_va)) { refill: page =3D __page_frag_cache_refill(nc, gfp_mask); if (!page) return NULL; =20 -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - /* if size can vary use size else just use PAGE_SIZE */ - size =3D nc->size; -#endif + encoded_va =3D nc->encoded_va; + size =3D page_frag_cache_page_size(encoded_va); + /* Even if we own the page, we do not use atomic_set(). * This would break get_page_unless_zero() users. */ page_ref_add(page, PAGE_FRAG_CACHE_MAX_SIZE); =20 /* reset page count bias and remaining to start of new frag */ - nc->pfmemalloc =3D page_is_pfmemalloc(page); nc->pagecnt_bias =3D PAGE_FRAG_CACHE_MAX_SIZE + 1; nc->remaining =3D size; + } else { + size =3D page_frag_cache_page_size(encoded_va); } =20 remaining =3D nc->remaining & align_mask; @@ -107,13 +112,13 @@ void *__page_frag_alloc_va_align(struct page_frag_cac= he *nc, return NULL; } =20 - page =3D virt_to_page(nc->va); + page =3D virt_to_page((void *)encoded_va); =20 if (!page_ref_sub_and_test(page, nc->pagecnt_bias)) goto refill; =20 - if (unlikely(nc->pfmemalloc)) { - free_unref_page(page, compound_order(page)); + if (unlikely(encoded_page_pfmemalloc(encoded_va))) { + free_unref_page(page, encoded_page_order(encoded_va)); goto refill; } =20 @@ -128,7 +133,7 @@ void *__page_frag_alloc_va_align(struct page_frag_cache= *nc, nc->pagecnt_bias--; nc->remaining =3D remaining - fragsz; =20 - return nc->va + (size - remaining); + return encoded_page_address(encoded_va) + (size - remaining); } EXPORT_SYMBOL(__page_frag_alloc_va_align); =20 --=20 2.33.0