linux-kernel - [PATCH 2/4] zsmalloc: add single-page object fastpath in unmap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1341263752-10210-3-git-send-email-sjenning@linux.vnet.ibm.com>
Date:	Mon,  2 Jul 2012 16:15:50 -0500
From:	Seth Jennings <sjenning@...ux.vnet.ibm.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Seth Jennings <sjenning@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Nitin Gupta <ngupta@...are.org>,
	Minchan Kim <minchan@...nel.org>,
	Robert Jennings <rcj@...ux.vnet.ibm.com>, linux-mm@...ck.org,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] zsmalloc: add single-page object fastpath in unmap

Improve zs_unmap_object() performance by adding a fast path for
objects that don't span pages.

Signed-off-by: Seth Jennings <sjenning@...ux.vnet.ibm.com>
---
 drivers/staging/zsmalloc/zsmalloc-main.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c
index a7a6f22..4942d41 100644
--- a/drivers/staging/zsmalloc/zsmalloc-main.c
+++ b/drivers/staging/zsmalloc/zsmalloc-main.c
@@ -774,6 +774,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle)
 	}
 
 	zs_copy_map_object(area->vm_buf, page, off, class->size);
+	area->vm_addr = NULL;
 	return area->vm_buf;
 }
 EXPORT_SYMBOL_GPL(zs_map_object);
@@ -788,6 +789,14 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
 	struct size_class *class;
 	struct mapping_area *area;
 
+	area = &__get_cpu_var(zs_map_area);
+	if (area->vm_addr) {
+		/* single-page object fastpath */
+		kunmap_atomic(area->vm_addr);
+		put_cpu_var(zs_map_area);
+		return;
+	}
+
 	BUG_ON(!handle);
 
 	obj_handle_to_location(handle, &page, &obj_idx);
@@ -795,11 +804,7 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
 	class = &pool->size_class[class_idx];
 	off = obj_idx_to_offset(page, obj_idx, class->size);
 
-	area = &__get_cpu_var(zs_map_area);
-	if (off + class->size <= PAGE_SIZE)
-		kunmap_atomic(area->vm_addr);
-	else
-		zs_copy_unmap_object(area->vm_buf, page, off, class->size);
+	zs_copy_unmap_object(area->vm_buf, page, off, class->size);
 	put_cpu_var(zs_map_area);
 }
 EXPORT_SYMBOL_GPL(zs_unmap_object);
-- 
1.7.9.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/