On a x86_64, with configured with allmodconfig, pahole states that the
regmap structure is:

	/* size: 1048, cachelines: 17, members: 78 */
	/* sum members: 1006, holes: 9, sum holes: 35 */
	/* padding: 7 */
	/* member types with holes: 2, total: 2 */
	/* last cacheline: 24 bytes */

So, when such a struct is allocated, 2048 bytes are allocated, with most of
this space being wasted.

Move a few bools so that the size is reduced to 1024.

After this change, pahole gives:

	/* size: 1024, cachelines: 16, members: 78 */
	/* sum members: 1006, holes: 6, sum holes: 18 */
	/* member types with holes: 2, total: 2 */

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
Compile tested only.

More could be done, to be more future-proof, but the changes would be more
invasive.
---
 drivers/base/regmap/internal.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index bdb450436cbc..6f31240ee4a9 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -73,12 +73,12 @@ struct regmap {
 	void *bus_context;
 	const char *name;
 
-	bool async;
 	spinlock_t async_lock;
 	wait_queue_head_t async_waitq;
 	struct list_head async_list;
 	struct list_head async_free;
 	int async_ret;
+	bool async;
 
 #ifdef CONFIG_DEBUG_FS
 	bool debugfs_disable;
@@ -117,8 +117,6 @@ struct regmap {
 		    void *val_buf, size_t val_size);
 	int (*write)(void *context, const void *data, size_t count);
 
-	bool defer_caching;
-
 	unsigned long read_flag_mask;
 	unsigned long write_flag_mask;
 
@@ -127,6 +125,8 @@ struct regmap {
 	int reg_stride;
 	int reg_stride_order;
 
+	bool defer_caching;
+
 	/* If set, will always write field to HW. */
 	bool force_write_field;
 
@@ -161,6 +161,9 @@ struct regmap {
 	struct reg_sequence *patch;
 	int patch_regs;
 
+	/* if set, the regmap core can sleep */
+	bool can_sleep;
+
 	/* if set, converts bulk read to single read */
 	bool use_single_read;
 	/* if set, converts bulk write to single write */
@@ -176,9 +179,6 @@ struct regmap {
 	void *selector_work_buf;	/* Scratch buffer used for selector */
 
 	struct hwspinlock *hwlock;
-
-	/* if set, the regmap core can sleep */
-	bool can_sleep;
 };
 
 struct regcache_ops {
-- 
2.48.1

On Fri, 24 Jan 2025 14:37:58 +0100, Christophe JAILLET wrote:
> On a x86_64, with configured with allmodconfig, pahole states that the
> regmap structure is:
> 
> 	/* size: 1048, cachelines: 17, members: 78 */
> 	/* sum members: 1006, holes: 9, sum holes: 35 */
> 	/* padding: 7 */
> 	/* member types with holes: 2, total: 2 */
> 	/* last cacheline: 24 bytes */
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git for-next

Thanks!

[1/1] regmap: Reorder 'struct regmap'
      commit: 995cf0e014b0144edf1125668a97c252c5ab775e

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark