From 84e6f56be9c68b59aca51544f7ee33706542d7bc Mon Sep 17 00:00:00 2001
From: Pasha Tatashin <pasha.tatashin@soleen.com>
Date: Mon, 5 Feb 2024 15:32:41 +0000
Subject: [PATCH] iommu/iova: use named kmem_cache for iova magazines
The magazine buffers can take gigabytes of kmem memory, dominating all
other allocations. For observability purpose create named slab cache so
the iova magazine memory overhead can be clearly observed.
With this change:
> slabtop -o | head
Active / Total Objects (% used) : 869731 / 952904 (91.3%)
Active / Total Slabs (% used) : 103411 / 103974 (99.5%)
Active / Total Caches (% used) : 135 / 211 (64.0%)
Active / Total Size (% used) : 395389.68K / 411430.20K (96.1%)
Minimum / Average / Maximum Object : 0.02K / 0.43K / 8.00K
OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
244412 244239 99% 1.00K 61103 4 244412K iommu_iova_magazine
91636 88343 96% 0.03K 739 124 2956K kmalloc-32
75744 74844 98% 0.12K 2367 32 9468K kernfs_node_cache
On this machine it is now clear that magazine use 242M of kmem memory.
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
[ rm: adjust to rework of iova_cache_{get,put} ]
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Link: https://lore.kernel.org/r/dc5c51aaba50906a92b9ba1a5137ed462484a7be.1707144953.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
drivers/iommu/iova.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index b5de865ee50b2..d59d0ea2fd219 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -590,6 +590,8 @@ struct iova_rcache {
struct delayed_work work;
};
+static struct kmem_cache *iova_magazine_cache;
+
unsigned long iova_rcache_range(void)
{
return PAGE_SIZE << (IOVA_RANGE_CACHE_MAX_SIZE - 1);
@@ -599,7 +601,7 @@ static struct iova_magazine *iova_magazine_alloc(gfp_t flags)
{
struct iova_magazine *mag;
- mag = kmalloc(sizeof(*mag), flags);
+ mag = kmem_cache_alloc(iova_magazine_cache, flags);
if (mag)
mag->size = 0;
@@ -608,7 +610,7 @@ static struct iova_magazine *iova_magazine_alloc(gfp_t flags)
static void iova_magazine_free(struct iova_magazine *mag)
{
- kfree(mag);
+ kmem_cache_free(iova_magazine_cache, mag);
}
static void
@@ -953,6 +955,12 @@ int iova_cache_get(void)
if (!iova_cache)
goto out_err;
+ iova_magazine_cache = kmem_cache_create("iommu_iova_magazine",
+ sizeof(struct iova_magazine),
+ 0, SLAB_HWCACHE_ALIGN, NULL);
+ if (!iova_magazine_cache)
+ goto out_err;
+
err = cpuhp_setup_state_multi(CPUHP_IOMMU_IOVA_DEAD, "iommu/iova:dead",
NULL, iova_cpuhp_dead);
if (err) {
@@ -968,6 +976,7 @@ int iova_cache_get(void)
out_err:
kmem_cache_destroy(iova_cache);
+ kmem_cache_destroy(iova_magazine_cache);
mutex_unlock(&iova_cache_mutex);
return err;
}
@@ -984,6 +993,7 @@ void iova_cache_put(void)
if (!iova_cache_users) {
cpuhp_remove_multi_state(CPUHP_IOMMU_IOVA_DEAD);
kmem_cache_destroy(iova_cache);
+ kmem_cache_destroy(iova_magazine_cache);
}
mutex_unlock(&iova_cache_mutex);
}
--
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