50 lines
1.8 KiB
Diff
50 lines
1.8 KiB
Diff
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Thu, 20 Jun 2024 12:53:06 +0200
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Subject: [PATCH 3/3] zram: Shrink zram_table_entry::flags.
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.11/older/patches-6.11-rt7.tar.xz
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The zram_table_entry::flags member is of type long and uses 8 bytes on a
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64bit architecture. With a PAGE_SIZE of 256KiB we have PAGE_SHIFT of 18
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which in turn leads to __NR_ZRAM_PAGEFLAGS = 27. This still fits in an
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ordinary integer.
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By reducing the size of `flags' to four bytes, the size of the struct
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goes back to 16 bytes. The padding between the lock and ac_time (if
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enabled) is also gone.
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Make zram_table_entry::flags an unsigned int and update the build test
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to reflect the change.
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Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Link: https://lore.kernel.org/20240906141520.730009-4-bigeasy@linutronix.de
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---
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drivers/block/zram/zram_drv.c | 3 ++-
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drivers/block/zram/zram_drv.h | 2 +-
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2 files changed, 3 insertions(+), 2 deletions(-)
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--- a/drivers/block/zram/zram_drv.c
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+++ b/drivers/block/zram/zram_drv.c
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@@ -2404,9 +2404,10 @@ static void destroy_devices(void)
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static int __init zram_init(void)
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{
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+ struct zram_table_entry zram_te;
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int ret;
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- BUILD_BUG_ON(__NR_ZRAM_PAGEFLAGS > BITS_PER_LONG);
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+ BUILD_BUG_ON(__NR_ZRAM_PAGEFLAGS > sizeof(zram_te.flags) * 8);
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ret = cpuhp_setup_state_multi(CPUHP_ZCOMP_PREPARE, "block/zram:prepare",
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zcomp_cpu_up_prepare, zcomp_cpu_dead);
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--- a/drivers/block/zram/zram_drv.h
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+++ b/drivers/block/zram/zram_drv.h
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@@ -66,7 +66,7 @@ struct zram_table_entry {
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unsigned long handle;
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unsigned long element;
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};
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- unsigned long flags;
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+ unsigned int flags;
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spinlock_t lock;
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#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
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ktime_t ac_time;
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