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Optimize callout handline via static timer wheel

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The number of callouts is a compile-time constant in libbsd.  Use this
in struct callout_cpu and avoid dynamic allocation of tables.  This
signficantly reduces the count of load instructions in the callout
handling.
This commit is contained in:
Sebastian Huber 2017-08-04 14:32:19 +02:00
parent cf447b951a
commit a85d90007e
2 changed files with 17 additions and 3 deletions
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18
freebsd/sys/kern/kern_timeout.c
View File

@ -128,11 +128,16 @@ SYSCTL_INT(_kern, OID_AUTO, pin_default_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &p
SYSCTL_INT(_kern, OID_AUTO, pin_pcpu_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_pcpu_swi,
0, "Pin the per-CPU swis (except PCPU 0, which is also default");
#ifndef __rtems__
/*
* TODO:
* allocate more timeout table slots when table overflows.
*/
u_int callwheelsize, callwheelmask;
#else /* __rtems__ */
#define callwheelsize (2 * ncallout)
#define callwheelmask (callwheelsize - 1)
#endif /* __rtems__ */
/*
* The callout cpu exec entities represent informations necessary for
@ -170,10 +175,13 @@ struct callout_cpu {
struct cc_exec cc_exec_entity;
#endif /* __rtems__ */
struct callout *cc_next;
#ifndef __rtems__
struct callout *cc_callout;
struct callout_list *cc_callwheel;
#ifndef __rtems__
struct callout_tailq cc_expireq;
#else /* __rtems__ */
struct callout cc_callout[ncallout];
struct callout_list cc_callwheel[callwheelsize];
#endif /* __rtems__ */
struct callout_slist cc_callfree;
sbintime_t cc_firstevent;
@ -359,8 +367,10 @@ callout_callwheel_init(void *dummy)
* Calculate callout wheel size, should be next power of two higher
* than 'ncallout'.
*/
#ifndef __rtems__
callwheelsize = 1 << fls(ncallout);
callwheelmask = callwheelsize - 1;
#endif /* __rtems__ */
#ifndef __rtems__
/*
@ -380,8 +390,10 @@ callout_callwheel_init(void *dummy)
timeout_cpu = PCPU_GET(cpuid);
#endif /* __rtems__ */
cc = CC_CPU(timeout_cpu);
#ifndef __rtems__
cc->cc_callout = malloc(ncallout * sizeof(struct callout),
M_CALLOUT, M_WAITOK);
#endif /* __rtems__ */
callout_cpu_init(cc, timeout_cpu);
}
#ifndef __rtems__
@ -400,8 +412,10 @@ callout_cpu_init(struct callout_cpu *cc, int cpu)
mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
SLIST_INIT(&cc->cc_callfree);
cc->cc_inited = 1;
#ifndef __rtems__
cc->cc_callwheel = malloc(sizeof(struct callout_list) * callwheelsize,
M_CALLOUT, M_WAITOK);
#endif /* __rtems__ */
for (i = 0; i < callwheelsize; i++)
LIST_INIT(&cc->cc_callwheel[i]);
#ifndef __rtems__
@ -412,8 +426,10 @@ callout_cpu_init(struct callout_cpu *cc, int cpu)
cc_cce_cleanup(cc, i);
snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name),
"callwheel cpu %d", cpu);
#ifndef __rtems__
if (cc->cc_callout == NULL) /* Only cpu0 handles timeout(9) */
return;
#endif /* __rtems__ */
for (i = 0; i < ncallout; i++) {
c = &cc->cc_callout[i];
callout_init(c, 0);

2
rtemsbsd/include/machine/rtems-bsd-kernel-namespace.h
View File

@ -472,8 +472,6 @@
#define callout_schedule_on _bsd_callout_schedule_on
#define _callout_stop_safe _bsd__callout_stop_safe
#define callout_when _bsd_callout_when
#define callwheelmask _bsd_callwheelmask
#define callwheelsize _bsd_callwheelsize
#define camellia_decrypt _bsd_camellia_decrypt
#define camellia_decrypt128 _bsd_camellia_decrypt128
#define camellia_decrypt256 _bsd_camellia_decrypt256