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Fri, 29 May 2026 12:41:02 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 64TCexFL26607912 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 29 May 2026 12:40:59 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1C31A20043; Fri, 29 May 2026 12:40:59 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5C1CE20040; Fri, 29 May 2026 12:40:57 +0000 (GMT) Received: from li-7bb28a4c-2dab-11b2-a85c-887b5c60d769.ibm.com.com (unknown [9.124.221.69]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 29 May 2026 12:40:57 +0000 (GMT) From: Shrikanth Hegde To: christophe.leroy@csgroup.eu, maddy@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, tglx@kernel.org Cc: sshegde@linux.ibm.com, linux-kernel@vger.kernel.org Subject: [PATCH v2 3/3] powerpc/irq: Suppress unlikely interrupt stats by default Date: Fri, 29 May 2026 18:10:45 +0530 Message-ID: <20260529124045.1208539-4-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260529124045.1208539-1-sshegde@linux.ibm.com> References: <20260529124045.1208539-1-sshegde@linux.ibm.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=L4MtheT8 c=1 sm=1 tr=0 ts=6a198960 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=HwhMAjjRhnxDVlPREfwA:9 X-Proofpoint-ORIG-GUID: PAV-6-Ot_Aw9KfM20SDoMXTYyojfAlk0 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTI5MDEyNiBTYWx0ZWRfX45AGDvuIbZf0 2Ul7z2VANi5/wtqM5gfLpSphbjt/K5tb7iPfwa+y1Y2kbXq79yMZpB56/KEi1Qkft6zOyiiA5sw B+lZZviPlumFnyq6cC2Ioiz5sfCanF6WmmBZQkyUhDYCIqCAW9j1ScoocfV9XcVNm8JDqw+8/Yu c0w2/VjH0MJtZjOWb9fP6uaYAv20gbfN/DIXNXTca5cs3G/EkucK42cfcN9vRJqHUWBlN70Cz6U YYjz08SPJwipestScjO+lyX6U8i+6aybeBROmvXx1fF0EydlViuLzQcIABHkC/sQJ2n9xSFvFbS Mcag/tcTmu1UVxhP98t8Qqz7+BvhZ4cZqjz0ugBPp7wO8Ht1Rwra6qTe30e0XRvESs559Urb/fn VsKoQdZjcdKcTKv8YPMh2jFoXB5M4hSvxQpHV4LjGKrpAOhPx/QjcRG1LHSM/AnHB/ubiXwBi0F YW9kWpFTIYLUWyiTZ0Q== X-Proofpoint-GUID: PAV-6-Ot_Aw9KfM20SDoMXTYyojfAlk0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-05-29_03,2026-05-28_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 lowpriorityscore=0 suspectscore=0 clxscore=1015 malwarescore=0 bulkscore=0 impostorscore=0 adultscore=0 priorityscore=1501 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2605290126 Some interrupts are always zero and that is expected since they occur very rarely and are mostly error indications. Don't print them by default. "MCE" - "Machine check exceptions" "NMI" - "System Reset interrupts" Print them if they occur once. Maintain a bitmap to know which interrupts are to be printed. Time taken to read /proc/interrupts 1000 times. Base and v6 details can be found in cover-letter. Base : 103us v6 : 63us v6+patch 1+2 : 57us v6+patch 1+2+3 : 54us Patch 3 shows an additional 5% gain compared to patch 1+2. So it does make sense to print them only if they are ever set. Note: Since /proc/interrupts depend on kconfig and arch dependent, userspace tools don't make explicit assumptions. Signed-off-by: Shrikanth Hegde --- arch/powerpc/include/asm/hardirq.h | 1 + arch/powerpc/kernel/irq.c | 37 +++++++++++++++++++++++++++--- arch/powerpc/kernel/traps.c | 4 ++-- 3 files changed, 37 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/include/asm/hardirq.h b/arch/powerpc/include/asm/hardirq.h index 38098e35b241..be6cd5aab016 100644 --- a/arch/powerpc/include/asm/hardirq.h +++ b/arch/powerpc/include/asm/hardirq.h @@ -31,6 +31,7 @@ DECLARE_PER_CPU(unsigned int, __softirq_pending); #define local_softirq_pending_ref __softirq_pending #define inc_irq_stat(index) __this_cpu_inc(irq_stat.counts[IRQ_COUNT_##index]) +void inc_irq_stat_and_enable(enum irq_stat_counts which); #define __ARCH_IRQ_STAT #define __ARCH_IRQ_EXIT_IRQS_DISABLED diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c index e67a18f62142..0a6a0e707fe8 100644 --- a/arch/powerpc/kernel/irq.c +++ b/arch/powerpc/kernel/irq.c @@ -87,9 +87,13 @@ u32 tau_interrupts(unsigned long cpu); struct irq_stat_info { const char *symbol; const char *text; + int optional; }; -#define ISE(idx, sym, txt)[IRQ_COUNT_##idx] = { .symbol = sym, .text = txt} +/* ISE - IRQ STAT ENABLED, ISC - IRQ STAT CONDITIONAL */ +#define ISE(idx, sym, txt)[IRQ_COUNT_##idx] = { .symbol = sym, .text = txt, .optional = 0} +#define ISC(idx, sym, txt)[IRQ_COUNT_##idx] = { .symbol = sym, .text = txt, .optional = 1} + static struct irq_stat_info irq_stat_info[IRQ_COUNT_MAX] __ro_after_init = { ISE(LOC_TIMER, "LOC", " Local timer interrupts for timer event device\n"), @@ -97,8 +101,8 @@ static struct irq_stat_info irq_stat_info[IRQ_COUNT_MAX] __ro_after_init = { ISE(OTHER_TIMER, "LOC", " Local timer interrupts for others\n"), ISE(SPURIOUS, "SPU", " Spurious interrupts\n"), ISE(PMI, "PMI", " Performance monitoring interrupts\n"), - ISE(MCE, "MCE", " Machine check exceptions\n"), - ISE(NMI_SRESET, "NMI", " System Reset interrupts\n"), + ISC(MCE, "MCE", " Machine check exceptions\n"), + ISC(NMI_SRESET, "NMI", " System Reset interrupts\n"), #ifdef CONFIG_PPC_WATCHDOG ISE(WATCHDOG, "WDG", " Watchdog soft-NMI interrupts\n"), #endif @@ -107,11 +111,25 @@ static struct irq_stat_info irq_stat_info[IRQ_COUNT_MAX] __ro_after_init = { #endif }; +/* + * Used for default disabled counters to increment the stats and to enable the + * entry for /proc/interrupts output. + */ +static DECLARE_BITMAP(irq_stat_count_show, IRQ_COUNT_MAX) __read_mostly; +void inc_irq_stat_and_enable(enum irq_stat_counts which) +{ + __this_cpu_inc(irq_stat.counts[which]); + set_bit(which, irq_stat_count_show); +} + int arch_show_interrupts(struct seq_file *p, int prec) { const struct irq_stat_info *info = irq_stat_info; for (unsigned int i = 0; i < ARRAY_SIZE(irq_stat_info); i++, info++) { + if (info->optional && !test_bit(i, irq_stat_count_show)) + continue; + seq_printf(p, "%*s:", prec, info->symbol); irq_proc_emit_counts(p, &irq_stat.counts[i]); seq_puts(p, info->text); @@ -138,6 +156,19 @@ int arch_show_interrupts(struct seq_file *p, int prec) return 0; } +static int __init irq_init_stats(void) +{ + struct irq_stat_info *info = irq_stat_info; + + for (unsigned int i = 0; i < ARRAY_SIZE(irq_stat_info); i++, info++) { + if (info->optional == 0) + set_bit(i, irq_stat_count_show); + } + + return 0; +} +late_initcall(irq_init_stats); + /* * /proc/stat helpers */ diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index a8f15154bd9a..3eacbd20fc80 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -459,7 +459,7 @@ DEFINE_INTERRUPT_HANDLER_NMI(system_reset_exception) } hv_nmi_check_nonrecoverable(regs); - inc_irq_stat(NMI_SRESET); + inc_irq_stat_and_enable(IRQ_COUNT_NMI_SRESET); /* See if any machine dependent calls */ if (ppc_md.system_reset_exception) { @@ -816,7 +816,7 @@ static void __machine_check_exception(struct pt_regs *regs) { int recover = 0; - inc_irq_stat(MCE); + inc_irq_stat_and_enable(IRQ_COUNT_MCE); add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE); -- 2.47.3