From: Shrikanth Hegde <sshegde@linux.ibm.com>
To: maddy@linux.ibm.com, linuxppc-dev@lists.ozlabs.org,
peterz@infradead.org, tim.c.chen@linux.intel.com
Cc: sshegde@linux.ibm.com, christophe.leroy@csgroup.eu,
linux-kernel@vger.kernel.org, ritesh.list@gmail.com,
kprateek.nayak@amd.com, yu.c.chen@intel.com,
vineethr@linux.ibm.com, vincent.guittot@linaro.org,
srikar@linux.ibm.com, npiggin@gmail.com, mpe@ellerman.id.au
Subject: [PATCH 3/4] powerpc/topology: Update mc/pkg flags based on llc_override
Date: Mon, 12 Oct 2026 15:50:36 +0530 [thread overview]
Message-ID: <20261012102037.2477378-4-sshegde@linux.ibm.com> (raw)
In-Reply-To: <20261012102037.2477378-1-sshegde@linux.ibm.com>
Update the flags passed for building the scheduler topology.
SD_SHARE_LLC is used to determine the highest domain where the LLC is.
Also when set at a particular domain, all the child domains are expected
to have it set as well.
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
---
arch/powerpc/kernel/smp.c | 63 +++++++++++++++++++++++++--------------
1 file changed, 40 insertions(+), 23 deletions(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 433757511adb..4b6512d25f73 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -141,6 +141,24 @@ volatile unsigned int cpu_callin_map[NR_CPUS];
int smt_enabled_at_boot = 1;
+enum llc_override_values {
+ LLC_OVERRIDE_DISABLED,
+ LLC_OVERRIDE_SMT,
+ LLC_OVERRIDE_MC,
+ LLC_OVERRIDE_PKG,
+};
+
+static int llc_override;
+static int llc_override_changed;
+static DEFINE_MUTEX(llc_override_mutex);
+
+static const char * const llc_override_str[] = {
+ [LLC_OVERRIDE_DISABLED] = "0",
+ [LLC_OVERRIDE_SMT] = "smt",
+ [LLC_OVERRIDE_MC] = "mc",
+ [LLC_OVERRIDE_PKG] = "pkg",
+};
+
/*
* Returns 1 if the specified cpu should be brought up during boot.
* Used to inhibit booting threads if they've been disabled or
@@ -1022,14 +1040,31 @@ static int powerpc_shared_cache_flags(void)
return SD_SHARE_LLC;
}
-static int powerpc_shared_proc_flags(void)
+static int powerpc_mc_flags(void)
{
+ int flags = 0;
+
if (static_branch_unlikely(&splpar_asym_pack))
- return SD_ASYM_PACKING;
+ flags |= SD_ASYM_PACKING;
- return 0;
+ if (READ_ONCE(llc_override) >= LLC_OVERRIDE_MC)
+ flags |= SD_SHARE_LLC;
+
+ return flags;
}
+static int powerpc_pkg_flags(void)
+{
+ int flags = 0;
+
+ if (static_branch_unlikely(&splpar_asym_pack))
+ flags |= SD_ASYM_PACKING;
+
+ if (READ_ONCE(llc_override) >= LLC_OVERRIDE_PKG)
+ flags |= SD_SHARE_LLC;
+
+ return flags;
+}
/*
* We can't just pass cpu_l2_cache_mask() directly because
* returns a non-const pointer and the compiler barfs on that.
@@ -1737,10 +1772,10 @@ static void __init build_sched_topology(void)
if (has_coregroup_support()) {
powerpc_topology[i++] =
- SDTL_INIT(tl_mc_mask, powerpc_shared_proc_flags, MC);
+ SDTL_INIT(tl_mc_mask, powerpc_mc_flags, MC);
}
- powerpc_topology[i++] = SDTL_INIT(tl_pkg_mask, powerpc_shared_proc_flags, PKG);
+ powerpc_topology[i++] = SDTL_INIT(tl_pkg_mask, powerpc_pkg_flags, PKG);
/* There must be one trailing NULL entry left. */
BUG_ON(i >= ARRAY_SIZE(powerpc_topology) - 1);
@@ -1828,24 +1863,6 @@ void __noreturn arch_cpu_idle_dead(void)
#endif
-enum llc_override_values {
- LLC_OVERRIDE_DISABLED,
- LLC_OVERRIDE_SMT,
- LLC_OVERRIDE_MC,
- LLC_OVERRIDE_PKG,
-};
-
-static int llc_override;
-static int llc_override_changed;
-static DEFINE_MUTEX(llc_override_mutex);
-
-static const char * const llc_override_str[] = {
- [LLC_OVERRIDE_DISABLED] = "0",
- [LLC_OVERRIDE_SMT] = "smt",
- [LLC_OVERRIDE_MC] = "mc",
- [LLC_OVERRIDE_PKG] = "pkg",
-};
-
static ssize_t llc_override_get(struct file *file, char __user *ubuf,
size_t count, loff_t *ppos)
{
--
2.52.0
next prev parent reply other threads:[~2026-10-12 10:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-12 10:20 [PATCH 0/4] powerpc/topology: Introduce llc_override debugfs Shrikanth Hegde
2026-10-12 10:20 ` [PATCH 1/4] powerpc/topology: Introduce llc_override debug knob Shrikanth Hegde
2026-10-12 12:14 ` Srikar Dronamraju
2026-10-12 14:10 ` Shrikanth Hegde
2026-10-12 10:20 ` [PATCH 2/4] powerpc/topology: Add docs for llc_override Shrikanth Hegde
2026-10-12 10:20 ` Shrikanth Hegde [this message]
2026-10-12 10:20 ` [PATCH 4/4] powerpc/topology: Rebuild sched domains on llc_override change Shrikanth Hegde
2026-10-12 12:19 ` [PATCH 0/4] powerpc/topology: Introduce llc_override debugfs Srikar Dronamraju
2026-10-12 14:14 ` Shrikanth Hegde
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