From nobody Fri Sep 20 01:19:05 2024 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) (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 8F5DB13F441; Fri, 19 Jul 2024 09:37:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.188 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721381836; cv=none; b=lr8IqG7jYl9bY/yeQ/MJcqL5gGaJdlXVeaj8dwCEtFJnu0lfDU/syGd33ItMs1/jdKQ5jvmZ6CQaPBRdk4Bb0G3FTm69mlRxXgB/GTIC4vW4BROpiWGbVZmt2mt40kB3mGiD29qtqueu7wDfevQE5yRNx4K9lVNoKMTWrQRUGnQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721381836; c=relaxed/simple; bh=pQJlYjiv5DR6baOXwSyh0wpn0yBBKxQtqaysVKkIO9k=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=rtCTb3kJI0NKWkPZ0PRs0WJ447HtBFTOsa9as+zWqrUyCTMLEONQ6UBIc4voexTf6RoU0bPl7JKLc5ZjF6eRIJAs5PKTeenGY644GT4U5knmxmTbHUj5Pj562+u+q5iiu868JMaunqKe9qWOSMJWTzu1NjvZIIsxgu8/Ql7wAfY= 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=45.249.212.188 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 [172.19.88.194]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4WQPfl6g7Bzdj4Q; Fri, 19 Jul 2024 17:35:27 +0800 (CST) Received: from dggpemf200006.china.huawei.com (unknown [7.185.36.61]) by mail.maildlp.com (Postfix) with ESMTPS id 9DB601402E2; Fri, 19 Jul 2024 17:37:12 +0800 (CST) Received: from localhost.localdomain (10.69.192.56) 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; Fri, 19 Jul 2024 17:37:12 +0800 From: Yunsheng Lin To: , , CC: , , Yunsheng Lin , Alexander Duyck , Andrew Morton , Subject: [RFC v11 07/14] mm: page_frag: reuse existing space for 'size' and 'pfmemalloc' Date: Fri, 19 Jul 2024 17:33:31 +0800 Message-ID: <20240719093338.55117-8-linyunsheng@huawei.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20240719093338.55117-1-linyunsheng@huawei.com> References: <20240719093338.55117-1-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 | 49 +++++++++++++++++++++++++++++++-- mm/page_frag_cache.c | 49 +++++++++++++++------------------ 3 files changed, 77 insertions(+), 37 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 ef1572f11248..12a16f8e8ad0 100644 --- a/include/linux/page_frag_cache.h +++ b/include/linux/page_frag_cache.h @@ -3,19 +3,64 @@ #ifndef _LINUX_PAGE_FRAG_CACHE_H #define _LINUX_PAGE_FRAG_CACHE_H =20 +#include +#include #include #include #include #include =20 +#define PAGE_FRAG_CACHE_ORDER_MASK GENMASK(7, 0) +#define PAGE_FRAG_CACHE_PFMEMALLOC_BIT BIT(8) +#define PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT 8 + +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); + +#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) + return (unsigned long)va | order | + (pfmemalloc << PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT); +#else + return (unsigned long)va | + (pfmemalloc << PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT); +#endif +} + +static inline unsigned long encoded_page_order(unsigned long encoded_va) +{ +#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) + return encoded_va & PAGE_FRAG_CACHE_ORDER_MASK; +#else + return 0; +#endif +} + +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 b12496f05c4a..7928e5d50711 100644 --- a/mm/page_frag_cache.c +++ b/mm/page_frag_cache.c @@ -22,7 +22,7 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, gfp_t gfp_mask) { - unsigned int page_size =3D PAGE_FRAG_CACHE_MAX_SIZE; + unsigned long order =3D PAGE_FRAG_CACHE_MAX_ORDER; struct page *page =3D NULL; gfp_t gfp =3D gfp_mask; =20 @@ -35,28 +35,27 @@ static struct page *__page_frag_cache_refill(struct pag= e_frag_cache *nc, if (unlikely(!page)) { page =3D alloc_pages_node(NUMA_NO_NODE, gfp, 0); if (unlikely(!page)) { - nc->va =3D NULL; + nc->encoded_va =3D 0; return NULL; } =20 - page_size =3D PAGE_SIZE; + order =3D 0; } =20 -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - nc->size =3D page_size; -#endif - nc->va =3D page_address(page); + 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 @@ -73,36 +72,30 @@ void *__page_frag_alloc_va_align(struct page_frag_cache= *nc, unsigned int fragsz, gfp_t gfp_mask, unsigned int align_mask) { - unsigned int size =3D PAGE_SIZE; - 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; } =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 - + size =3D page_frag_cache_page_size(encoded_va); remaining =3D nc->remaining & align_mask; if (unlikely(remaining < fragsz)) { if (unlikely(fragsz > PAGE_SIZE)) { @@ -118,13 +111,15 @@ 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))) { + VM_BUG_ON(compound_order(page) !=3D + encoded_page_order(encoded_va)); + free_unref_page(page, encoded_page_order(encoded_va)); goto refill; } =20 @@ -141,7 +136,7 @@ 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