The patch titled
RCU: move three variables to __read_mostly to save space
has been removed from the -mm tree. Its filename was
rcu-move-three-variables-to-__read_mostly-to-save-space.patch
This patch was dropped because Changes in git-x86 broke it
------------------------------------------------------
Subject: RCU: move three variables to __read_mostly to save space
From: Eric Dumazet <dada1@xxxxxxxxxxxxx>
I noticed this vmlinux layout on i686 (where CONFIG_X86_L1_CACHE_SHIFT = 7) :
c06cdab4 d pid_caches_lh
c06cdb00 d qlowmark
c06cdb04 d qhimark
c06cdb08 d blimit
c06cdb80 d rcu_ctrlblk
c06cdc80 d rcu_bh_ctrlblk
This means that qlowmark, qhimark and blimit use a whole 128 bytes cache line.
Linker is not smart enough for us.
Moving these three variables to read_mostly section saves 116 (128-12) bytes.
# size vmlinux vmlinux.before_patch
text data bss dec hex filename
6343966 490818 630784 7465568 71ea60 vmlinux
6343966 490930 630784 7465680 71ead0 vmlinux.before_patch
Signed-off-by: Eric Dumazet <dada1@xxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Dipankar Sarma <dipankar@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/rcupdate.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -puN kernel/rcupdate.c~rcu-move-three-variables-to-__read_mostly-to-save-space kernel/rcupdate.c
--- a/kernel/rcupdate.c~rcu-move-three-variables-to-__read_mostly-to-save-space
+++ a/kernel/rcupdate.c
@@ -75,9 +75,9 @@ DEFINE_PER_CPU(struct rcu_data, rcu_bh_d
/* Fake initialization required by compiler */
static DEFINE_PER_CPU(struct tasklet_struct, rcu_tasklet) = {NULL};
-static int blimit = 10;
-static int qhimark = 10000;
-static int qlowmark = 100;
+static int blimit __read_mostly = 10;
+static int qhimark __read_mostly = 10000;
+static int qlowmark __read_mostly = 100;
static atomic_t rcu_barrier_cpu_count;
static DEFINE_MUTEX(rcu_barrier_mutex);
_
Patches currently in -mm which might be from dada1@xxxxxxxxxxxxx are
parport-dev-timeslice-is-an-unsigned-long-not-an-int.patch
git-net.patch
git-sched.patch
percpu-__percpu_alloc_mask-can-dynamically-size-percpu_data.patch
get-rid-of-nr_open-and-introduce-a-sysctl_nr_open.patch
get-rid-of-nr_open-and-introduce-a-sysctl_nr_open-fix.patch
rcu-move-three-variables-to-__read_mostly-to-save-space.patch
-
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