linux-kernel - [POC 08/12] fs/dcache.c: access dentry_cache via rai

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Date:   Thu, 18 Oct 2018 00:33:28 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, "H . Peter Anvin" <hpa@...or.com>,
        Ingo Molnar <mingo@...nel.org>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [POC 08/12] fs/dcache.c: access dentry_cache via rai_load

This avoids a cacheline access to get the value of the dentry_cache
pointer in the places that do a kmem_cache_*(dentry_cache, ...);

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 fs/dcache.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 2e7e8d85e9b4..1d54dfb38c9d 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -30,6 +30,7 @@
 #include <linux/bit_spinlock.h>
 #include <linux/rculist_bl.h>
 #include <linux/list_lru.h>
+#include <linux/rai.h>
 #include "internal.h"
 #include "mount.h"
 
@@ -76,7 +77,8 @@ __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
 
 EXPORT_SYMBOL(rename_lock);
 
-static struct kmem_cache *dentry_cache __read_mostly;
+static struct kmem_cache *__dentry_cache __read_mostly;
+#define dentry_cache rai_load(__dentry_cache)
 
 const struct qstr empty_name = QSTR_INIT("", 0);
 EXPORT_SYMBOL(empty_name);
@@ -3088,7 +3090,7 @@ static void __init dcache_init(void)
 	 * but it is probably not worth it because of the cache nature
 	 * of the dcache.
 	 */
-	dentry_cache = KMEM_CACHE_USERCOPY(dentry,
+	__dentry_cache = KMEM_CACHE_USERCOPY(dentry,
 		SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD|SLAB_ACCOUNT,
 		d_iname);
 
-- 
2.19.1.6.gbde171bbf5