From: Jon Derrick <jonathan.derrick@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>, <linux-kernel@vger.kernel.org>
Cc: <linux-nvme@lists.infradead.org>,
Jon Derrick <jonathan.derrick@intel.com>
Subject: [PATCH] genirq/affinity: report extra vectors on uneven nodes
Date: Wed, 7 Aug 2019 14:10:51 -0600 [thread overview]
Message-ID: <20190807201051.32662-1-jonathan.derrick@intel.com> (raw)
The current irq spreading algorithm spreads vectors amongst cpus evenly
per node. If a node has more cpus than another node, the extra vectors
being spread may not be reported back to the caller.
This is most apparent with the NVMe driver and nr_cpus < vectors, where
the underreporting results in the caller's WARN being triggered:
irq_build_affinity_masks()
...
if (nr_present < numvecs)
WARN_ON(nr_present + nr_others < numvecs);
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
---
kernel/irq/affinity.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index 4352b08ae48d..9beafb8c7e92 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -127,7 +127,8 @@ static int __irq_build_affinity_masks(unsigned int startvec,
}
for_each_node_mask(n, nodemsk) {
- unsigned int ncpus, v, vecs_to_assign, vecs_per_node;
+ unsigned int ncpus, v, vecs_to_assign, total_vecs_to_assign,
+ vecs_per_node;
/* Spread the vectors per node */
vecs_per_node = (numvecs - (curvec - firstvec)) / nodes;
@@ -141,14 +142,16 @@ static int __irq_build_affinity_masks(unsigned int startvec,
/* Account for rounding errors */
extra_vecs = ncpus - vecs_to_assign * (ncpus / vecs_to_assign);
+ total_vecs_to_assign = vecs_to_assign + extra_vecs;
- for (v = 0; curvec < last_affv && v < vecs_to_assign;
+ for (v = 0; curvec < last_affv && v < total_vecs_to_assign;
curvec++, v++) {
cpus_per_vec = ncpus / vecs_to_assign;
/* Account for extra vectors to compensate rounding errors */
if (extra_vecs) {
cpus_per_vec++;
+ v++;
--extra_vecs;
}
irq_spread_init_one(&masks[curvec].mask, nmsk,
--
2.20.1
next reply other threads:[~2019-08-07 20:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 20:10 Jon Derrick [this message]
2019-08-08 7:04 ` [PATCH] genirq/affinity: report extra vectors on uneven nodes Thomas Gleixner
2019-08-08 16:32 ` Keith Busch
2019-08-08 22:46 ` Derrick, Jonathan
2019-08-08 23:08 ` Keith Busch
2019-08-09 3:04 ` Ming Lei
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