hwpmc: improve diagnostic messages for invalid tunables

Replace printf() with log(LOG_WARNING, ...) in pmclog_initialize()
so that tunable validation failures are visible in dmesg and
/var/log/messages rather than only on the early console.

Also improve the messages to report both the invalid value and the
default it resets to, making it easier for users to understand why
their tunable was ignored.

While here, adjust some whitespacing/style.

Reviewed by:	Ali Mashtizadeh <ali@mashtizadeh.com>, mhorne
MFC after:	1 week
Sponsored by:	NLINK (nlink.com.br)
Differential Revision:	https://reviews.freebsd.org/D56029

sys/dev/hwpmc/hwpmc_logging.c

@@ -58,6 +58,7 @@
 #include <sys/uio.h>
 #include <sys/unistd.h>
 #include <sys/vnode.h>
+#include <sys/syslog.h>
 
 #if defined(__i386__) || defined(__amd64__)
 #include <machine/clock.h>
@@ -1236,24 +1237,39 @@ pmclog_initialize(void)
 	struct pmclog_buffer *plb;
 	int domain, ncpus, total;
 
-	if (pmclog_buffer_size <= 0 || pmclog_buffer_size > 16*1024) {
-		(void) printf("hwpmc: tunable logbuffersize=%d must be "
-					  "greater than zero and less than or equal to 16MB.\n",
-					  pmclog_buffer_size);
+	if (pmclog_buffer_size <= 0 ||
+	    pmclog_buffer_size > PMC_LOG_BUFFER_SIZE_MAX) {
+		log(LOG_WARNING,
+		    "hwpmc: logbuffersize=%d must be greater than zero "
+		    "and less than or equal to %d, resetting to %d\n",
+		    pmclog_buffer_size, PMC_LOG_BUFFER_SIZE_MAX,
+		    PMC_LOG_BUFFER_SIZE);
+
 		pmclog_buffer_size = PMC_LOG_BUFFER_SIZE;
 	}
 
 	if (pmc_nlogbuffers_pcpu <= 0) {
-		(void) printf("hwpmc: tunable nlogbuffers=%d must be greater "
-					  "than zero.\n", pmc_nlogbuffers_pcpu);
+		log(LOG_WARNING,
+		    "hwpmc: nbuffers_pcpu=%d must be greater than zero, "
+		    "resetting to %d\n",
+		    pmc_nlogbuffers_pcpu, PMC_NLOGBUFFERS_PCPU);
+
 		pmc_nlogbuffers_pcpu = PMC_NLOGBUFFERS_PCPU;
 	}
-	if (pmc_nlogbuffers_pcpu*pmclog_buffer_size > 32*1024) {
-		(void) printf("hwpmc: memory allocated pcpu must be less than 32MB (is %dK).\n",
-					  pmc_nlogbuffers_pcpu*pmclog_buffer_size);
+
+	if (pmc_nlogbuffers_pcpu * pmclog_buffer_size >
+	    PMC_NLOGBUFFERS_PCPU_MEM_MAX) {
+		log(LOG_WARNING,
+		    "hwpmc: nbuffers_pcpu=%d * logbuffersize=%d exceeds "
+		    "%dMB per CPU limit, resetting to defaults (%d * %d)\n",
+		    pmc_nlogbuffers_pcpu, pmclog_buffer_size,
+		    PMC_NLOGBUFFERS_PCPU_MEM_MAX / 1024,
+		    PMC_NLOGBUFFERS_PCPU, PMC_LOG_BUFFER_SIZE);
+
 		pmc_nlogbuffers_pcpu = PMC_NLOGBUFFERS_PCPU;
 		pmclog_buffer_size = PMC_LOG_BUFFER_SIZE;
 	}
+
 	for (domain = 0; domain < vm_ndomains; domain++) {
 		ncpus = pmc_dom_hdrs[domain]->pdbh_ncpus;
 		total = ncpus * pmc_nlogbuffers_pcpu;
@@ -1270,6 +1286,7 @@ pmclog_initialize(void)
 			pmc_plb_rele_unlocked(plb);
 		}
 	}
+
 	mtx_init(&pmc_kthread_mtx, "pmc-kthread", "pmc-sleep", MTX_DEF);
 }
 

sys/sys/pmc.h

@@ -661,7 +661,9 @@ struct pmc_op_caps {
 #define	PMC_HASH_SIZE				1024
 #define	PMC_MTXPOOL_SIZE			2048
 #define	PMC_LOG_BUFFER_SIZE			256
+#define	PMC_LOG_BUFFER_SIZE_MAX			(16 * 1024)
 #define	PMC_NLOGBUFFERS_PCPU			32
+#define	PMC_NLOGBUFFERS_PCPU_MEM_MAX		(32 * 1024)
 #define	PMC_NSAMPLES				256
 #define	PMC_CALLCHAIN_DEPTH			128
 #define	PMC_THREADLIST_MAX			128