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Message-Id: <334a5e2d8c9a05ce7cbac126bfbc6b39d05e1c9c.1676635829.git.christophe.jaillet@wanadoo.fr>
Date: Fri, 17 Feb 2023 13:10:46 +0100
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
Len Brown <lenb@...nel.org>
Cc: linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
linux-acpi@...r.kernel.org
Subject: [PATCH] ACPI: EC: Reorder fields in 'struct acpi_ec'
Group some variables based on their sizes to reduce hole and avoid padding.
On x86_64, this shrinks the size of 'struct acpi_ec'
from 520 to 512 bytes.
This size is much better when the struct is kmalloc()'ed.
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
Using pahole
Before:
======
struct acpi_ec {
acpi_handle handle; /* 0 8 */
acpi_handle address_space_handler_holder; /* 8 8 */
int gpe; /* 16 4 */
int irq; /* 20 4 */
long unsigned int command_addr; /* 24 8 */
long unsigned int data_addr; /* 32 8 */
bool global_lock; /* 40 1 */
/* XXX 7 bytes hole, try to pack */
long unsigned int flags; /* 48 8 */
long unsigned int reference_count; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct mutex mutex; /* 64 160 */
/* --- cacheline 3 boundary (192 bytes) was 32 bytes ago --- */
wait_queue_head_t wait; /* 224 88 */
/* --- cacheline 4 boundary (256 bytes) was 56 bytes ago --- */
struct list_head list; /* 312 16 */
/* --- cacheline 5 boundary (320 bytes) was 8 bytes ago --- */
struct transaction * curr; /* 328 8 */
spinlock_t lock; /* 336 72 */
/* --- cacheline 6 boundary (384 bytes) was 24 bytes ago --- */
struct work_struct work; /* 408 80 */
/* --- cacheline 7 boundary (448 bytes) was 40 bytes ago --- */
long unsigned int timestamp; /* 488 8 */
enum acpi_ec_event_state event_state; /* 496 4 */
unsigned int events_to_process; /* 500 4 */
unsigned int events_in_progress; /* 504 4 */
unsigned int queries_in_progress; /* 508 4 */
/* --- cacheline 8 boundary (512 bytes) --- */
bool busy_polling; /* 512 1 */
/* XXX 3 bytes hole, try to pack */
unsigned int polling_guard; /* 516 4 */
/* size: 520, cachelines: 9, members: 22 */
/* sum members: 510, holes: 2, sum holes: 10 */
/* last cacheline: 8 bytes */
};
After:
=====
struct acpi_ec {
acpi_handle handle; /* 0 8 */
acpi_handle address_space_handler_holder; /* 8 8 */
int gpe; /* 16 4 */
int irq; /* 20 4 */
long unsigned int command_addr; /* 24 8 */
long unsigned int data_addr; /* 32 8 */
bool global_lock; /* 40 1 */
bool busy_polling; /* 41 1 */
/* XXX 2 bytes hole, try to pack */
unsigned int polling_guard; /* 44 4 */
long unsigned int flags; /* 48 8 */
long unsigned int reference_count; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct mutex mutex; /* 64 160 */
/* --- cacheline 3 boundary (192 bytes) was 32 bytes ago --- */
wait_queue_head_t wait; /* 224 88 */
/* --- cacheline 4 boundary (256 bytes) was 56 bytes ago --- */
struct list_head list; /* 312 16 */
/* --- cacheline 5 boundary (320 bytes) was 8 bytes ago --- */
struct transaction * curr; /* 328 8 */
spinlock_t lock; /* 336 72 */
/* --- cacheline 6 boundary (384 bytes) was 24 bytes ago --- */
struct work_struct work; /* 408 80 */
/* --- cacheline 7 boundary (448 bytes) was 40 bytes ago --- */
long unsigned int timestamp; /* 488 8 */
enum acpi_ec_event_state event_state; /* 496 4 */
unsigned int events_to_process; /* 500 4 */
unsigned int events_in_progress; /* 504 4 */
unsigned int queries_in_progress; /* 508 4 */
/* size: 512, cachelines: 8, members: 22 */
/* sum members: 510, holes: 1, sum holes: 2 */
};
---
drivers/acpi/internal.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 06ad497067ac..acfdd23c8dec 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -179,6 +179,8 @@ struct acpi_ec {
unsigned long command_addr;
unsigned long data_addr;
bool global_lock;
+ bool busy_polling;
+ unsigned int polling_guard;
unsigned long flags;
unsigned long reference_count;
struct mutex mutex;
@@ -192,8 +194,6 @@ struct acpi_ec {
unsigned int events_to_process;
unsigned int events_in_progress;
unsigned int queries_in_progress;
- bool busy_polling;
- unsigned int polling_guard;
};
extern struct acpi_ec *first_ec;
--
2.34.1
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