The patch titled
fdtable: Avoid fdset cacheline ping-pong.
has been removed from the -mm tree. Its filename was
fdtable-implement-new-pagesize-based-fdtable-allocator-avoid-fdset-cacheline-ping-pong.patch
This patch was dropped because it was folded into fdtable-implement-new-pagesize-based-fdtable-allocator.patch
------------------------------------------------------
Subject: fdtable: Avoid fdset cacheline ping-pong.
From: Vadim Lobanov <vlobanov@xxxxxxxxxxxxx>
This is a performance optimization for the fdtable code. When expanding
the fdtable for a task, we want to allocate at least L1_CACHE_BYTES for the
new fdset memory -- this will ensure that the fdsets of two different tasks
will not share the same cacheline, causing lots of cacheline ping-pongs.
Signed-off-by: Vadim Lobanov <vlobanov@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/file.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN fs/file.c~fdtable-implement-new-pagesize-based-fdtable-allocator-avoid-fdset-cacheline-ping-pong fs/file.c
--- a/fs/file.c~fdtable-implement-new-pagesize-based-fdtable-allocator-avoid-fdset-cacheline-ping-pong
+++ a/fs/file.c
@@ -158,7 +158,8 @@ static struct fdtable * alloc_fdtable(un
if (!data)
goto out_fdt;
fdt->fd = (struct file **)data;
- data = alloc_fdmem(2 * nr / BITS_PER_BYTE);
+ data = alloc_fdmem(max_t(unsigned int,
+ 2 * nr / BITS_PER_BYTE, L1_CACHE_BYTES));
if (!data)
goto out_arr;
fdt->open_fds = (fd_set *)data;
_
Patches currently in -mm which might be from vlobanov@xxxxxxxxxxxxx are
fdtable-delete-pointless-code-in-dup_fd.patch
fdtable-make-fdarray-and-fdsets-equal-in-size.patch
fdtable-remove-the-free_files-field.patch
fdtable-implement-new-pagesize-based-fdtable-allocator.patch
fdtable-implement-new-pagesize-based-fdtable-allocator-avoid-fdset-cacheline-ping-pong.patch
fdtable-make-fdarray-and-fdsets-equal-in-size-slim.patch
-
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