linux-kernel - [PATCH 4/4] zcache: add pageframes count once compress zero-filled pages twice

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Date:	Wed, 13 Mar 2013 15:05:21 +0800
From:	Wanpeng Li <liwanp@...ux.vnet.ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	Seth Jennings <sjenning@...ux.vnet.ibm.com>,
	Konrad Rzeszutek Wilk <konrad@...nok.org>,
	Minchan Kim <minchan@...nel.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>
Subject: [PATCH 4/4] zcache: add pageframes count once compress zero-filled pages twice

Since zbudpage consist of two zpages, two zero-filled pages compression
contribute to one [eph|pers]pageframe count accumulated.

Signed-off-by: Wanpeng Li <liwanp@...ux.vnet.ibm.com>
---
 drivers/staging/zcache/zcache-main.c |   25 +++++++++++++++++++++++--
 1 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index dd52975..7860ff0 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -544,6 +544,8 @@ static struct page *zcache_evict_eph_pageframe(void);
 static void *zcache_pampd_eph_create(char *data, size_t size, bool raw,
 					struct tmem_handle *th)
 {
+	static ssize_t second_eph_zero_page;
+	static atomic_t second_eph_zero_page_atomic = ATOMIC_INIT(0);
 	void *pampd = NULL, *cdata = data;
 	unsigned clen = size;
 	bool zero_filled = false;
@@ -561,7 +563,14 @@ static void *zcache_pampd_eph_create(char *data, size_t size, bool raw,
 		clen = 0;
 		zero_filled = true;
 		zcache_pages_zero++;
-		goto got_pampd;
+		second_eph_zero_page = atomic_inc_return(
+				&second_eph_zero_page_atomic);
+		if (second_eph_zero_page % 2 == 1)
+			goto got_pampd;
+		else {
+			atomic_sub(2, &second_eph_zero_page_atomic);
+			goto count_zero_page;
+		}
 	}
 	kunmap_atomic(user_mem);
 
@@ -597,6 +606,7 @@ static void *zcache_pampd_eph_create(char *data, size_t size, bool raw,
 create_in_new_page:
 	pampd = (void *)zbud_create_prep(th, true, cdata, clen, newpage);
 	BUG_ON(pampd == NULL);
+count_zero_page:
 	zcache_eph_pageframes =
 		atomic_inc_return(&zcache_eph_pageframes_atomic);
 	if (zcache_eph_pageframes > zcache_eph_pageframes_max)
@@ -621,6 +631,8 @@ out:
 static void *zcache_pampd_pers_create(char *data, size_t size, bool raw,
 					struct tmem_handle *th)
 {
+	static ssize_t second_pers_zero_page;
+	static atomic_t second_pers_zero_page_atomic = ATOMIC_INIT(0);
 	void *pampd = NULL, *cdata = data;
 	unsigned clen = size, zero_filled = 0;
 	struct page *page = (struct page *)(data), *newpage;
@@ -644,7 +656,15 @@ static void *zcache_pampd_pers_create(char *data, size_t size, bool raw,
 		clen = 0;
 		zero_filled = 1;
 		zcache_pages_zero++;
-		goto got_pampd;
+		second_pers_zero_page = atomic_inc_return(
+				&second_pers_zero_page_atomic);
+		if (second_pers_zero_page % 2 == 1)
+			goto got_pampd;
+		else {
+			atomic_sub(2, &second_pers_zero_page_atomic);
+			goto count_zero_page;
+		}
+
 	}
 	kunmap_atomic(user_mem);
 
@@ -698,6 +718,7 @@ create_pampd:
 create_in_new_page:
 	pampd = (void *)zbud_create_prep(th, false, cdata, clen, newpage);
 	BUG_ON(pampd == NULL);
+count_zero_page:
 	zcache_pers_pageframes =
 		atomic_inc_return(&zcache_pers_pageframes_atomic);
 	if (zcache_pers_pageframes > zcache_pers_pageframes_max)
-- 
1.7.7.6

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