Arnaldo Carvalho de Melo 00f62f614b ring_buffer: pahole struct ring_buffer ...

While fixing some bugs in pahole (built-in.o files were not being
processed due to relocation problems) I found out about these packable
structures:

$ pahole --packable kernel/trace/ring_buffer.o  | grep ring
ring_buffer	72	64	8
ring_buffer_per_cpu	112	104	8

If we take a look at the current layout of struct ring_buffer we can see
that we have two 4 bytes holes.

$ pahole -C ring_buffer kernel/trace/ring_buffer.o
struct ring_buffer {
	unsigned int               pages;           /*     0     4 */
	unsigned int               flags;           /*     4     4 */
	int                        cpus;            /*     8     4 */

	/* XXX 4 bytes hole, try to pack */

	cpumask_var_t              cpumask;         /*    16     8 */
	atomic_t                   record_disabled; /*    24     4 */

	/* XXX 4 bytes hole, try to pack */

	struct mutex               mutex;           /*    32    32 */
	/* --- cacheline 1 boundary (64 bytes) --- */
	struct ring_buffer_per_cpu * * buffers;     /*    64     8 */

	/* size: 72, cachelines: 2, members: 7 */
	/* sum members: 64, holes: 2, sum holes: 8 */
	/* last cacheline: 8 bytes */
};

So, if I ask pahole to reorganize it:

$ pahole -C ring_buffer --reorganize kernel/trace/ring_buffer.o

struct ring_buffer {
	unsigned int               pages;           /*     0     4 */
	unsigned int               flags;           /*     4     4 */
	int                        cpus;            /*     8     4 */
	atomic_t                   record_disabled; /*    12     4 */
	cpumask_var_t              cpumask;         /*    16     8 */
	struct mutex               mutex;           /*    24    32 */
	struct ring_buffer_per_cpu * * buffers;     /*    56     8 */
	/* --- cacheline 1 boundary (64 bytes) --- */

	/* size: 64, cachelines: 1, members: 7 */
};   /* saved 8 bytes and 1 cacheline! */

We get it using just one 64 bytes cacheline.

To see what it did:

$ pahole -C ring_buffer --reorganize --show_reorg_steps \
	kernel/trace/ring_buffer.o | grep \/
/* Moving 'record_disabled' from after 'cpumask' to after 'cpus' */

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2009-02-11 13:21:40 +01:00

..

irq

Merge branch 'core/xen' into x86/urgent

2009-02-04 14:54:56 +01:00

power

Merge branches 'release', 'asus', 'bugzilla-12450', 'cpuidle', 'debug', 'ec', 'misc', 'printk' and 'processor' into release

2009-02-07 01:34:56 -05:00

time

hrtimers: allow the hot-unplugging of all cpus

2009-01-30 22:35:29 +01:00

trace

ring_buffer: pahole struct ring_buffer

2009-02-11 13:21:40 +01:00

.gitignore

Update kernel/.gitignore with new auto-generated files

2008-02-09 23:27:01 -08:00

acct.c

[CVE-2009-0029] System call wrappers part 04

2009-01-14 14:15:19 +01:00

async.c

async: use list_move_tail

2009-02-08 10:00:26 -08:00

audit_tree.c

audit: validate comparison operations, store them in sane form

2009-01-04 15:14:42 -05:00

audit.c

[PATCH] fix broken timestamps in AVC generated by kernel threads

2008-12-09 02:27:41 -05:00

audit.h

fixing audit rule ordering mess, part 1

2009-01-04 15:14:41 -05:00

auditfilter.c

audit: validate comparison operations, store them in sane form

2009-01-04 15:14:42 -05:00

auditsc.c

make sure that filterkey of task,always rules is reported

2009-01-04 15:14:42 -05:00

backtracetest.c

backtrace: replace timer with tasklet + completions

2008-06-27 18:09:16 +02:00

bounds.c

Add kbuild.h that contains common definitions for kbuild users

2008-04-29 08:06:29 -07:00

capability.c

[CVE-2009-0029] System call wrappers part 04

2009-01-14 14:15:19 +01:00

cgroup_debug.c

cgroups: fix probable race with put_css_set[_taskexit] and find_css_set

2008-10-20 08:52:38 -07:00

cgroup_freezer.c

freezer_cg: disable writing freezer.state of root cgroup

2008-11-12 17:17:16 -08:00

cgroup.c

cgroup: fix root_count when mount fails due to busy subsystem

2009-01-29 18:04:45 -08:00

compat.c

Allow times and time system calls to return small negative values

2009-01-06 15:59:13 -08:00

configs.c

kernel/configs.c: remove useless comments

2008-10-20 08:52:34 -07:00

cpu.c

stop_machine/cpu hotplug: fix disable_nonboot_cpus

2009-01-07 11:36:14 -08:00

cpuset.c

cpuset: fix possible deadlock in async_rebuild_sched_domains

2009-01-19 02:44:00 +01:00

cred-internals.h

CRED: Inaugurate COW credentials

2008-11-14 10:39:23 +11:00

cred.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6

2009-01-09 13:59:25 -08:00

delayacct.c

schedstat: consolidate per-task cpu runtime stats

2008-12-18 13:54:01 +01:00

dma-coherent.c

dma-coherent: Restore dma_alloc_from_coherent() large alloc fall back policy.

2009-01-21 18:51:53 +09:00

dma.c

kernel/dma.c: remove a CVS keyword

2008-10-16 11:21:30 -07:00

exec_domain.c

[CVE-2009-0029] System call wrappers part 04

2009-01-14 14:15:19 +01:00

exit.c

[CVE-2009-0029] System call wrappers part 08

2009-01-14 14:15:21 +01:00

extable.c

tracing/function-graph-tracer: drop the kernel_text_address check

2009-02-09 10:51:38 +01:00

fork.c

fork.c: fix NULL pointer dereference when nr_threads == threads-max

2009-02-06 08:43:11 -08:00

freezer.c

freezer_cg: use thaw_process() in unfreeze_cgroup()

2008-10-30 11:38:45 -07:00

futex_compat.c

CRED: Use RCU to access another task's creds and to release a task's own creds

2008-11-14 10:39:19 +11:00

futex.c

[CVE-2009-0029] System call wrappers part 31

2009-01-14 14:15:31 +01:00

hrtimer.c

hrtimer: prevent negative expiry value after clock_was_set()

2009-01-30 22:35:34 +01:00

itimer.c

[CVE-2009-0029] System call wrappers part 05

2009-01-14 14:15:20 +01:00

kallsyms.c

Revert "kbuild: strip generated symbols from *.ko"

2009-01-14 21:38:20 +01:00

Kconfig.freezer

container freezer: implement freezer cgroup subsystem

2008-10-20 08:52:34 -07:00

Kconfig.hz

sched: fix SCHED_HRTICK dependency

2008-07-28 14:37:38 +02:00

Kconfig.preempt

rcu: provide RCU options on non-preempt architectures too

2008-12-25 09:31:28 +01:00

kexec.c

[CVE-2009-0029] System call wrappers part 07

2009-01-14 14:15:20 +01:00

kfifo.c

is_power_of_2: kernel/kfifo.c

2007-07-16 09:05:50 -07:00

kgdb.c

kgdb: call touch_softlockup_watchdog on resume

2008-10-06 13:50:59 -05:00

kmod.c

kmod: fix varargs kernel-doc

2009-01-06 15:59:27 -08:00

kprobes.c

kprobes: check CONFIG_FREEZER instead of CONFIG_PM

2009-01-16 14:32:17 -05:00

ksysfs.c

kernel/ksysfs.c:fix dependence on CONFIG_NET

2009-01-06 10:44:31 -08:00

kthread.c

tracepoints: add DECLARE_TRACE() and DEFINE_TRACE()

2008-11-16 09:01:36 +01:00

latencytop.c

KSYM_SYMBOL_LEN fixes

2008-12-10 08:01:54 -08:00

lockdep_internals.h

lockdep: build fix

2008-08-13 12:55:10 +02:00

lockdep_proc.c

lockstat: contend with points

2008-10-20 15:43:10 +02:00

lockdep.c

Merge branch 'core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2008-12-30 16:10:19 -08:00

Makefile

kernel/up.c: omit it if SMP=y, USE_GENERIC_SMP_HELPERS=n

2009-01-14 09:42:11 -08:00

marker.c

markers/tracpoints: fix non-modular build

2008-11-16 09:52:03 +01:00

module.c

tracing/function-graph-tracer: drop the kernel_text_address check

2009-02-09 10:51:38 +01:00

mutex-debug.c

mutex-debug: check mutex magic before owner

2008-05-16 16:53:35 +02:00

mutex-debug.h

…

mutex.c

mutex: __used is needed for function referenced only from inline asm

2008-11-24 10:00:28 +01:00

mutex.h

…

notifier.c

Merge commit 'v2.6.28-rc6' into core/debug

2008-11-26 08:22:50 +01:00

ns_cgroup.c

ns_cgroup: remove unused spinlock

2009-01-08 08:31:02 -08:00

nsproxy.c

User namespaces: set of cleanups (v2)

2008-11-24 18:57:41 -05:00

panic.c

oops: increment the oops UUID every time we oops

2009-01-06 15:59:12 -08:00

params.c

Fix compile warning in kernel/params.c

2008-10-23 12:09:00 -07:00

pid_namespace.c

pid_ns: (BUG 11391) change ->child_reaper when init->group_leader exits

2008-09-02 19:21:38 -07:00

pid.c

pid: generalize task_active_pid_ns

2009-01-08 08:31:12 -08:00

pm_qos_params.c

pm_qos_requirement might sleep

2008-09-02 19:21:40 -07:00

posix-cpu-timers.c

itimers: remove the per-cpu-ish-ness

2009-01-07 18:52:44 +01:00

posix-timers.c

[CVE-2009-0029] System call wrappers part 05

2009-01-14 14:15:20 +01:00

printk.c

[CVE-2009-0029] System call wrappers part 27

2009-01-14 14:15:29 +01:00

profile.c

profiling: fix broken profiling regression

2009-02-10 00:50:37 +01:00

ptrace.c

[CVE-2009-0029] System call wrappers part 27

2009-01-14 14:15:29 +01:00

rcuclassic.c

rcu: add __cpuinit to rcu_init_percpu_data()

2009-01-14 11:26:40 +01:00

rcupdate.c

rcu: eliminate synchronize_rcu_xxx macro

2009-01-05 10:18:08 +01:00

rcupreempt_trace.c

"Tree RCU": scalable classic RCU implementation

2008-12-18 21:56:04 +01:00

rcupreempt.c

rcu: eliminate synchronize_rcu_xxx macro

2009-01-05 10:18:08 +01:00

rcutorture.c

rcu: fix bug in rcutorture system-shutdown code

2009-01-07 23:36:25 +01:00

rcutree_trace.c

"Tree RCU": scalable classic RCU implementation

2008-12-18 21:56:04 +01:00

rcutree.c

rcu: add __cpuinit to rcu_init_percpu_data()

2009-01-14 11:26:40 +01:00

relay.c

Merge branches 'tracing/ftrace', 'tracing/kmemtrace' and 'linus' into tracing/core

2009-02-03 06:25:38 +01:00

res_counter.c

memcg: memory cgroup resource counters for hierarchy

2009-01-08 08:31:05 -08:00

resource.c

resources: fix parameter name and kernel-doc

2009-01-15 16:39:38 -08:00

rtmutex_common.h

Don't operate with pid_t in rtmutex tester

2008-02-08 09:22:41 -08:00

rtmutex-debug.c

Don't operate with pid_t in rtmutex tester

2008-02-08 09:22:41 -08:00

rtmutex-debug.h

…

rtmutex-tester.c

sysdev: Pass the attribute to the low level sysdev show/store function

2008-07-21 21:55:02 -07:00

rtmutex.c

hrtimer: convert kernel/* to the new hrtimer apis

2008-09-05 21:35:13 -07:00

rtmutex.h

…

rwsem.c

sched: mark rwsem functions as __sched for wchan/profiling

2007-12-18 15:21:13 +01:00

sched_clock.c

sched_clock: prevent scd->clock from moving backwards, take #2

2008-12-31 09:53:21 +01:00

sched_cpupri.c

sched: fix section mismatch

2009-01-06 11:07:15 +01:00

sched_cpupri.h

sched: convert struct cpupri_vec cpumask_var_t.

2008-11-24 17:52:22 +01:00

sched_debug.c

sched: partly revert "sched debug: remove NULL checking in print_cfs_rt_rq()"

2009-01-11 02:40:32 +01:00

sched_fair.c

sched: fix buddie group latency

2009-02-01 10:49:51 +01:00

sched_features.h

sched: backward looking buddy

2008-11-05 10:30:14 +01:00

sched_idletask.c

sched: add CONFIG_SMP consistency

2008-10-22 10:01:52 +02:00

sched_rt.c

sched_rt: don't use first_cpu on cpumask created with cpumask_and

2009-02-01 10:49:52 +01:00

sched_stats.h

itimers: remove the per-cpu-ish-ness

2009-01-07 18:52:44 +01:00

sched.c

Merge commit 'v2.6.29-rc4' into tracing/core

2009-02-09 10:32:48 +01:00

seccomp.c

make seccomp zerocost in schedule

2007-07-16 09:05:50 -07:00

semaphore.c

semaphore: __down_common: use signal_pending_state()

2008-08-05 14:33:47 -07:00

signal.c

signals, debug: fix BUG: using smp_processor_id() in preemptible code in print_fatal_signal()

2009-01-27 00:36:19 +01:00

smp.c

generic-ipi: use per cpu data for single cpu ipi calls

2009-01-30 18:31:08 +01:00

softirq.c

trace, lockdep: manual preempt count adding for local_bh_disable

2009-01-23 11:10:57 +01:00

softlockup.c

softlock: fix false panic which can occur if softlockup_thresh is reduced

2009-01-14 11:48:07 +01:00

spinlock.c

lockdep: spin_lock_nest_lock(), checkpatch fixes

2008-08-13 13:56:51 +02:00

srcu.c

make srcu_readers_active() static

2008-02-06 10:41:02 -08:00

stacktrace.c

stacktrace: provide save_stack_trace_tsk() weak alias

2008-12-25 11:44:43 +01:00

stop_machine.c

stop_machine: introduce stop_machine_create/destroy.

2009-01-05 08:40:14 +10:30

sys_ni.c

[CVE-2009-0029] Make sys_syslog a conditional system call

2009-01-14 14:15:16 +01:00

sys.c

revert "rlimit: permit setting RLIMIT_NOFILE to RLIM_INFINITY"

2009-02-05 12:56:47 -08:00

sysctl_check.c

[XFS] remove restricted chown parameter from xfs linux

2008-10-30 18:30:09 +11:00

sysctl.c

Merge branch 'core/debugobjects' into core/urgent

2009-01-22 10:03:02 +01:00

taskstats.c

cpumask: convert rest of files in kernel/

2009-01-01 10:12:28 +10:30

test_kprobes.c

kprobes: add tests for register_kprobes

2009-01-06 15:59:20 -08:00

time.c

[CVE-2009-0029] System call wrappers part 01

2009-01-14 14:15:18 +01:00

timeconst.pl

Make constants in kernel/timeconst.h fixed 64 bits

2008-05-02 16:18:42 -07:00

timer.c

[CVE-2009-0029] System call wrappers part 27

2009-01-14 14:15:29 +01:00

tracepoint.c

markers/tracpoints: fix non-modular build

2008-11-16 09:52:03 +01:00

tsacct.c

mm: introduce get_mm_hiwater_xxx(), fix taskstats->hiwater_xxx accounting

2009-01-06 15:59:09 -08:00

uid16.c

[CVE-2009-0029] System call wrappers part 19

2009-01-14 14:15:26 +01:00

up.c

smp_call_function_single(): be slightly less stupid, fix #2

2009-01-12 16:04:37 +01:00

user_namespace.c

User namespaces: set of cleanups (v2)

2008-11-24 18:57:41 -05:00

user.c

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2008-12-28 12:27:58 -08:00

utsname_sysctl.c

sysctl: simplify ->strategy

2008-10-16 11:21:47 -07:00

utsname.c

removed unused #include <linux/version.h>'s

2008-08-23 12:14:12 -07:00

wait.c

wait: prevent exclusive waiter starvation

2009-02-05 12:56:48 -08:00

workqueue.c

Merge branches 'tracing/ftrace', 'tracing/kmemtrace' and 'linus' into tracing/core

2009-02-03 06:25:38 +01:00