Re: [PATCH 05/10] slab: allow enable_cpu_cache to use preset values for its tunables

[Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>]

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On 07/25/2012 10:33 PM, Christoph Lameter wrote:
> On Wed, 25 Jul 2012, Glauber Costa wrote:
> 
>> It is certainly not through does the same method as SLAB, right ?
>> Writing to /proc/slabinfo gives me an I/O error
>> I assume it is something through sysfs, but schiming through the code
>> now, I can't find any per-cache tunables. Would you mind pointing me to
>> them?
> 
> The slab attributes in /sys/kernel/slab/<slabname>/<attr> can be modified
> for some values. I think that could be the default method for the future
> since it allows easy addition of new tunables as needed.
> 

Christoph, would the following PoC patch be enough?



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From 7c582c5c6321cbde93c5e73c6c2096b4432a2a04 Mon Sep 17 00:00:00 2001
From: Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
Date: Thu, 26 Jul 2012 15:19:08 +0400
Subject: [PATCH] slub propagation

---
 mm/slub.c |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/mm/slub.c b/mm/slub.c
index 55946c3..a136a75 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5130,6 +5130,10 @@ static ssize_t slab_attr_store(struct kobject *kobj,
 	struct slab_attribute *attribute;
 	struct kmem_cache *s;
 	int err;
+#ifdef CONFIG_MEMCG_KMEM
+	struct kmem_cache *c;
+	struct mem_cgroup_cache_params *p;
+#endif
 
 	attribute = to_slab_attr(attr);
 	s = to_slab(kobj);
@@ -5138,7 +5142,19 @@ static ssize_t slab_attr_store(struct kobject *kobj,
 		return -EIO;
 
 	err = attribute->store(s, buf, len);
+#ifdef CONFIG_MEMCG_KMEM
+	if (slab_state < FULL)
+		return err;
 
+	if ((err < 0) || (s->memcg_params.id == -1))
+		return err;
+
+	list_for_each_entry(p, &s->memcg_params.sibling_list, sibling_list) {
+		c = container_of(p, struct kmem_cache, memcg_params);
+		/* return value determined by the parent cache only */
+		attribute->store(c, buf, len);
+	}
+#endif
 	return err;
 }
 
-- 
1.7.10.4