git: 290a7adfb1df - stable/15 - hwpmc: improve diagnostic messages for invalid tunables

The branch stable/15 has been updated by mhorne:

URL: https://cgit.FreeBSD.org/src/commit/?id=290a7adfb1df0fb0e8ee4161cf002db929a10fc5

commit 290a7adfb1df0fb0e8ee4161cf002db929a10fc5
Author:     Paulo Fragoso <paulo@nlink.com.br>
AuthorDate: 2026-03-23 14:54:18 +0000
Commit:     Mitchell Horne <mhorne@FreeBSD.org>
CommitDate: 2026-04-16 15:18:25 +0000

    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
    
    (cherry picked from commit b3a18736ec2fc2bd097995dedd8d09e79bcb2056)
---
 sys/dev/hwpmc/hwpmc_logging.c | 35 ++++++++++++++++++++++++++---------
 sys/sys/pmc.h                 |  2 ++
 2 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/sys/dev/hwpmc/hwpmc_logging.c b/sys/dev/hwpmc/hwpmc_logging.c
index 8fd7ef06a977..4f507523b6ab 100644
--- a/sys/dev/hwpmc/hwpmc_logging.c
+++ b/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);
 }
 
diff --git a/sys/sys/pmc.h b/sys/sys/pmc.h
index 12b8ddcb156f..69399ec24743 100644
--- a/sys/sys/pmc.h
+++ b/sys/sys/pmc.h
@@ -649,7 +649,9 @@ struct pmc_op_getdyneventinfo {
 #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