diff options
| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2016-10-25 12:21:44 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2016-11-11 16:37:40 +0100 |
| commit | c360192bf4a8dc72f102dd6a4e1bf8bd0b404cfa (patch) | |
| tree | c54104bae43978dfe31e6fc2c9a4d996218379fd /arch/s390/include/asm/lowcore.h | |
| parent | 1993dbc7e09a7ffdd98975589aa83387928e9fe7 (diff) | |
s390/preempt: move preempt_count to the lowcore
Convert s390 to use a field in the struct lowcore for the CPU
preemption count. It is a bit cheaper to access a lowcore field
compared to a thread_info variable and it removes the depencency
on a task related structure.
bloat-o-meter on the vmlinux image for the default configuration
(CONFIG_PREEMPT_NONE=y) reports a small reduction in text size:
add/remove: 0/0 grow/shrink: 18/578 up/down: 228/-5448 (-5220)
A larger improvement is achieved with the default configuration
but with CONFIG_PREEMPT=y and CONFIG_DEBUG_PREEMPT=n:
add/remove: 2/6 grow/shrink: 59/4477 up/down: 1618/-228762 (-227144)
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/lowcore.h')
| -rw-r--r-- | arch/s390/include/asm/lowcore.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h index 7b93b78f423c..1df1e6215e85 100644 --- a/arch/s390/include/asm/lowcore.h +++ b/arch/s390/include/asm/lowcore.h @@ -126,7 +126,8 @@ struct lowcore { __u64 percpu_offset; /* 0x0378 */ __u64 vdso_per_cpu_data; /* 0x0380 */ __u64 machine_flags; /* 0x0388 */ - __u8 pad_0x0390[0x0398-0x0390]; /* 0x0390 */ + __u32 preempt_count; /* 0x0390 */ + __u8 pad_0x0394[0x0398-0x0394]; /* 0x0394 */ __u64 gmap; /* 0x0398 */ __u32 spinlock_lockval; /* 0x03a0 */ __u32 fpu_flags; /* 0x03a4 */ |