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Date:      Fri, 23 Jul 2010 16:46:42 +0000 (UTC)
From:      Andriy Gapon <avg@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r210422 - head/sys/kern
Message-ID:  <201007231646.o6NGkgiv053858@svn.freebsd.org>
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Author: avg
Date: Fri Jul 23 16:46:42 2010
New Revision: 210422
URL: http://svn.freebsd.org/changeset/base/210422

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

Modified:
  head/sys/kern/kern_cpu.c

Modified: head/sys/kern/kern_cpu.c
==============================================================================
--- head/sys/kern/kern_cpu.c	Fri Jul 23 15:32:44 2010	(r210421)
+++ head/sys/kern/kern_cpu.c	Fri Jul 23 16:46:42 2010	(r210422)
@@ -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_ARG
 
 	/* 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_ARG
 	error = sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);
 
 out:
-	free(levels, M_TEMP);
 	sbuf_delete(&sb);
 	return (error);
 }

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