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cpufreq: allocate long-lived buffer for handling of sysctl requests

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At present the cpufreq sysctl handler for current level setting would
allocate and deallocate a temporary buffer of 24KB even to handle a
read-only query.  This puts unnecessary load on memory subsystem when
current level is checked frequently, e.g. when the likes of powerd
and system monitoring software are running.
Change the strategy to allocating a long-lived buffer for handling the
requests.

Reviewed by:	njl
MFC after:	2 weeks
This commit is contained in:
Andriy Gapon 2010-07-23 16:46:42 +00:00
parent 5ee561ee3e
commit dac509311f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=210422
1 changed files with 6 additions and 7 deletions
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13
sys/kern/kern_cpu.c
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@ -76,6 +76,7 @@ struct cpufreq_softc {
device_t dev;
struct sysctl_ctx_list sysctl_ctx;
struct task startup_task;
struct cf_level *levels_buf;
};
struct cf_setting_array {
@ -180,6 +181,8 @@ cpufreq_attach(device_t dev)
CF_DEBUG("initializing one-time data for %s\n",
device_get_nameunit(dev));
sc->levels_buf = malloc(CF_MAX_LEVELS * sizeof(*sc->levels_buf),
M_DEVBUF, M_WAITOK);
SYSCTL_ADD_PROC(&sc->sysctl_ctx,
SYSCTL_CHILDREN(device_get_sysctl_tree(parent)),
OID_AUTO, "freq", CTLTYPE_INT | CTLFLAG_RW, sc, 0,
@ -227,6 +230,7 @@ cpufreq_detach(device_t dev)
numdevs = devclass_get_count(cpufreq_dc);
if (numdevs == 1) {
CF_DEBUG("final shutdown for %s\n", device_get_nameunit(dev));
free(sc->levels_buf, M_DEVBUF);
}
return (0);
@ -870,9 +874,7 @@ cpufreq_curr_sysctl(SYSCTL_HANDLER_ARGS)
devs = NULL;
sc = oidp->oid_arg1;
levels = malloc(CF_MAX_LEVELS * sizeof(*levels), M_TEMP, M_NOWAIT);
if (levels == NULL)
return (ENOMEM);
levels = sc->levels_buf;
error = CPUFREQ_GET(sc->dev, &levels[0]);
if (error)
@ -915,8 +917,6 @@ cpufreq_curr_sysctl(SYSCTL_HANDLER_ARGS)
out:
if (devs)
free(devs, M_TEMP);
if (levels)
free(levels, M_TEMP);
return (error);
}
@ -934,7 +934,7 @@ cpufreq_levels_sysctl(SYSCTL_HANDLER_ARGS)
/* Get settings from the device and generate the output string. */
count = CF_MAX_LEVELS;
levels = malloc(count * sizeof(*levels), M_TEMP, M_NOWAIT);
levels = sc->levels_buf;
if (levels == NULL) {
sbuf_delete(&sb);
return (ENOMEM);
@ -957,7 +957,6 @@ cpufreq_levels_sysctl(SYSCTL_HANDLER_ARGS)
error = sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);
out:
free(levels, M_TEMP);
sbuf_delete(&sb);
return (error);
}