Messages in this thread | | | Date | Thu, 12 Nov 2015 15:17:01 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH 3/3] tools/vm/slabinfo: update struct slabinfo members' types |
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On (11/11/15 21:07), David Rientjes wrote: [..] > > > > /* Object size */ > > > > - unsigned long long min_objsize = max, max_objsize = 0, avg_objsize; > > > > + unsigned int min_objsize = UINT_MAX, max_objsize = 0, avg_objsize; > > > > > > > > /* Number of partial slabs in a slabcache */ > > > > unsigned long long min_partial = max, max_partial = 0, > > > > > > avg_objsize should not be unsigned int. > > > > Hm. the assumption is that `avg_objsize' cannot be larger > > than `max_objsize', which is > > `int object_size;' in `struct kmem_cache' from slab_def.h > > and > > `unsigned int object_size;' in `struct kmem_cache' from slab.h. > > > > > > avg_objsize = total_used / total_objects; > > >
I'm not sure I clearly understand the problems you're pointing me to.
> This has nothing to do with object_size in the kernel.
what we have in slabinfo as slab_size(), ->object_size, etc. comming from slub's sysfs attrs:
chdir("/sys/kernel/slab") while readdir ... slab->object_size = get_obj("object_size"); slab->slab_size = get_obj("slab_size"); ...
and attr show handlers are:
... static ssize_t slab_size_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", s->size); } SLAB_ATTR_RO(slab_size);
static ssize_t object_size_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", s->object_size); } SLAB_ATTR_RO(object_size); ...
so those are sprintf("%d") of `struct kmem_cache'-s `int' values.
> total_used and total_objects are unsigned long long.
yes, that's correct. but `total_used / total_objects' cannot be larger that the size of the largest object, which is represented in the kernel and returned to user space as `int'. it must fit into `unsigned int'.
> If you need to convert max_objsize to be unsigned long long as > well, that would be better.
... in case if someday `struct kmem_cache' will be updated to keep `unsigned long' sized objects and sysfs attrs will do sprintf("%lu")? IOW, if slabs will keep objects bigger that 4gig?
-ss
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