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zram: Shrink zram_table_entry::flags.

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The zram_table_entry::flags member is of type long and uses 8 bytes on a
64bit architecture. With a PAGE_SIZE of 256KiB we have PAGE_SHIFT of 18
which in turn leads to __NR_ZRAM_PAGEFLAGS = 27. This still fits in an
ordinary integer.
By reducing the size of `flags' to four bytes, the size of the struct
goes back to 16 bytes. The padding between the lock and ac_time (if
enabled) is also gone.

Make zram_table_entry::flags an unsigned int and update the build test
to reflect the change.

Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20240906141520.730009-4-bigeasy@linutronix.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Sebastian Andrzej Siewior 2024-09-06 16:14:45 +02:00 committed by Jens Axboe
parent 6086aeb49e
commit 68d20eb60e
2 changed files with 3 additions and 2 deletions
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3
drivers/block/zram/zram_drv.c
View File

@ -2404,9 +2404,10 @@ static void destroy_devices(void)
static int __init zram_init(void)
{
struct zram_table_entry zram_te;
int ret;
BUILD_BUG_ON(__NR_ZRAM_PAGEFLAGS > BITS_PER_LONG);
BUILD_BUG_ON(__NR_ZRAM_PAGEFLAGS > sizeof(zram_te.flags) * 8);
ret = cpuhp_setup_state_multi(CPUHP_ZCOMP_PREPARE, "block/zram:prepare",
zcomp_cpu_up_prepare, zcomp_cpu_dead);

2
drivers/block/zram/zram_drv.h
View File

@ -66,7 +66,7 @@ struct zram_table_entry {
unsigned long handle;
unsigned long element;
};
unsigned long flags;
unsigned int flags;
spinlock_t lock;
#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
ktime_t ac_time;