From: Anton Blanchard <anton@samba.org>
To: benh@kernel.crashing.org
Cc: linuxppc-dev@ozlabs.org
Subject: [PATCH] powerpc: Reduce footprint of xics_ipi_struct
Date: Tue, 12 Jan 2010 21:58:05 +1100 [thread overview]
Message-ID: <20100112105805.GJ12666@kryten> (raw)
In-Reply-To: <20100112105642.GI12666@kryten>
Right now we allocate a cacheline sized NR_CPUS array for xics IPI
communication. Since irq_stat is now PowerPC specific and using
DECLARE_PER_CPU_SHARED_ALIGNED (which should mean remote writes to
this should not conflict with other per cpu data), we can put it in there.
On a kernel with NR_CPUS=1024, this saves quite a lot of memory:
text data bss dec hex filename
8767779 2944260 1505724 13217763 c9afe3 vmlinux.irq_cpustat
8767555 2813444 1505724 13086723 c7b003 vmlinux.xics
A saving of around 128kB.
Signed-off-by: Anton Blanchard <anton@samba.org>
---
Index: linux-cpumask/arch/powerpc/include/asm/hardirq.h
===================================================================
--- linux-cpumask.orig/arch/powerpc/include/asm/hardirq.h 2010-01-12 12:36:47.174226189 +1100
+++ linux-cpumask/arch/powerpc/include/asm/hardirq.h 2010-01-12 12:36:47.432976459 +1100
@@ -6,6 +6,9 @@
typedef struct {
unsigned int __softirq_pending;
+#if defined(CONFIG_XICS) && defined(CONFIG_SMP)
+ unsigned long xics_ipi;
+#endif
} ____cacheline_aligned irq_cpustat_t;
DECLARE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
Index: linux-cpumask/arch/powerpc/platforms/pseries/xics.c
===================================================================
--- linux-cpumask.orig/arch/powerpc/platforms/pseries/xics.c 2010-01-12 12:36:46.905477650 +1100
+++ linux-cpumask/arch/powerpc/platforms/pseries/xics.c 2010-01-12 12:40:54.782975198 +1100
@@ -514,15 +514,12 @@ static void __init xics_init_host(void)
/*
* XICS only has a single IPI, so encode the messages per CPU
*/
-struct xics_ipi_struct {
- unsigned long value;
- } ____cacheline_aligned;
-
-static struct xics_ipi_struct xics_ipi_message[NR_CPUS] __cacheline_aligned;
static inline void smp_xics_do_message(int cpu, int msg)
{
- set_bit(msg, &xics_ipi_message[cpu].value);
+ unsigned long *tgt = &(per_cpu(irq_stat, cpu).xics_ipi);
+
+ set_bit(msg, tgt);
mb();
if (firmware_has_feature(FW_FEATURE_LPAR))
lpar_qirr_info(cpu, IPI_PRIORITY);
@@ -548,25 +545,23 @@ void smp_xics_message_pass(int target, i
static irqreturn_t xics_ipi_dispatch(int cpu)
{
+ unsigned long *tgt = &(per_cpu(irq_stat, cpu).xics_ipi);
+
WARN_ON(cpu_is_offline(cpu));
mb(); /* order mmio clearing qirr */
- while (xics_ipi_message[cpu].value) {
- if (test_and_clear_bit(PPC_MSG_CALL_FUNCTION,
- &xics_ipi_message[cpu].value)) {
+ while (*tgt) {
+ if (test_and_clear_bit(PPC_MSG_CALL_FUNCTION, tgt)) {
smp_message_recv(PPC_MSG_CALL_FUNCTION);
}
- if (test_and_clear_bit(PPC_MSG_RESCHEDULE,
- &xics_ipi_message[cpu].value)) {
+ if (test_and_clear_bit(PPC_MSG_RESCHEDULE, tgt)) {
smp_message_recv(PPC_MSG_RESCHEDULE);
}
- if (test_and_clear_bit(PPC_MSG_CALL_FUNC_SINGLE,
- &xics_ipi_message[cpu].value)) {
+ if (test_and_clear_bit(PPC_MSG_CALL_FUNC_SINGLE, tgt)) {
smp_message_recv(PPC_MSG_CALL_FUNC_SINGLE);
}
#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
- if (test_and_clear_bit(PPC_MSG_DEBUGGER_BREAK,
- &xics_ipi_message[cpu].value)) {
+ if (test_and_clear_bit(PPC_MSG_DEBUGGER_BREAK, tgt)) {
smp_message_recv(PPC_MSG_DEBUGGER_BREAK);
}
#endif
next prev parent reply other threads:[~2010-01-12 10:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-12 10:56 [PATCH] powerpc: Reduce footprint of irq_stat Anton Blanchard
2010-01-12 10:58 ` Anton Blanchard [this message]
2010-02-01 5:18 ` [PATCH] powerpc: Reduce footprint of xics_ipi_struct Benjamin Herrenschmidt
2010-02-01 6:26 ` Anton Blanchard
2010-02-01 5:21 ` [PATCH] powerpc: Reduce footprint of irq_stat Benjamin Herrenschmidt
2010-02-01 5:44 ` Anton Blanchard
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