linux-kernel - [PATCH/RFC v2 3/3] tlb: mmu_gather: use batched table free if possible

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Date:   Sat, 18 Dec 2021 21:52:06 +0300
From:   Nikita Yushchenko <nikita.yushchenko@...tuozzo.com>
To:     Will Deacon <will@...nel.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nick Piggin <npiggin@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>, Sam Ravnborg <sam@...nborg.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-mm@...ck.org, kernel@...nvz.org
Subject: [PATCH/RFC v2 3/3] tlb: mmu_gather: use batched table free if possible

In case when __tlb_remove_table() is implemented via
free_page_and_swap_cache(), use free_pages_and_swap_cache_nolru() for
batch table removal.

This enables use of single release_pages() call instead of a loop
calling put_page(). This shall have better performance, especially when
memcg accounting is enabled.

Signed-off-by: Nikita Yushchenko <nikita.yushchenko@...tuozzo.com>
---
 mm/mmu_gather.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c
index eb2f30a92462..2e75d396bbad 100644
--- a/mm/mmu_gather.c
+++ b/mm/mmu_gather.c
@@ -98,15 +98,24 @@ static inline void __tlb_remove_table(void *table)
 {
 	free_page_and_swap_cache((struct page *)table);
 }
-#endif
 
-static void __tlb_remove_table_free(struct mmu_table_batch *batch)
+static inline void __tlb_remove_tables(void **tables, int nr)
+{
+	free_pages_and_swap_cache_nolru((struct page **)tables, nr);
+}
+#else
+static inline void __tlb_remove_tables(void **tables, int nr)
 {
 	int i;
 
-	for (i = 0; i < batch->nr; i++)
-		__tlb_remove_table(batch->tables[i]);
+	for (i = 0; i < nr; i++)
+		__tlb_remove_table(tables[i]);
+}
+#endif
 
+static void __tlb_remove_table_free(struct mmu_table_batch *batch)
+{
+	__tlb_remove_tables(batch->tables, batch->nr);
 	free_page((unsigned long)batch);
 }
 
-- 
2.30.2