Hello Andrew,
Thanks for your review.
2014-12-20 6:32 GMT+08:00 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>:
> On Fri, 19 Dec 2014 20:55:19 +0800 Ganesh Mahendran <opensource.ganesh@xxxxxxxxx> wrote:
>
>> Keeping fragmentation of zsmalloc in a low level is our target. But now
>> we still need to add the debug code in zsmalloc to get the quantitative data.
>>
>> This patch adds a new configuration CONFIG_ZSMALLOC_STAT to enable the
>> statistics collection for developers. Currently only the objects statatitics
>> in each class are collected. User can get the information via debugfs.
>> cat /sys/kernel/debug/zsmalloc/pool-1/...
>
> Is everyone OK with this now?
>
>> --- a/include/linux/zsmalloc.h
>> +++ b/include/linux/zsmalloc.h
>> @@ -48,4 +48,13 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle);
>>
>> unsigned long zs_get_total_pages(struct zs_pool *pool);
>>
>> +#ifdef CONFIG_ZSMALLOC_STAT
>> +int get_zs_pool_index(struct zs_pool *pool);
>
> The name is inconsistent with the rest of zsmalloc and with preferred
> kernel naming conventions. Should be "zs_get_pool_index".
Okay, I will modify it.
>
>> +#else
>> +static inline int get_zs_pool_index(struct zs_pool *pool)
>> +{
>> + return -1;
>> +}
>> +#endif
>> +
>> #endif
>> diff --git a/mm/Kconfig b/mm/Kconfig
>> index 1d1ae6b..95c5728 100644
>> --- a/mm/Kconfig
>> +++ b/mm/Kconfig
>>
>> ...
>>
>> +static int zs_stats_size_show(struct seq_file *s, void *v)
>> +{
>> + int i;
>> + struct zs_pool *pool = (struct zs_pool *)s->private;
>
> The typecast is unneeded and undesirable (it defeats typechecking).
>
>> + struct size_class *class;
>> + int objs_per_zspage;
>> + unsigned long obj_allocated, obj_used, pages_used;
>> + unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
>> +
>> + seq_printf(s, " %5s %5s %13s %10s %10s\n", "class", "size",
>> + "obj_allocated", "obj_used", "pages_used");
>> +
>> + for (i = 0; i < zs_size_classes; i++) {
>> + class = pool->size_class[i];
>> +
>> + if (class->index != i)
>> + continue;
>> +
>> + spin_lock(&class->lock);
>> + obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
>> + obj_used = zs_stat_get(class, OBJ_USED);
>> + spin_unlock(&class->lock);
>> +
>> + objs_per_zspage = get_maxobj_per_zspage(class->size,
>> + class->pages_per_zspage);
>> + pages_used = obj_allocated / objs_per_zspage *
>> + class->pages_per_zspage;
>> +
>> + seq_printf(s, " %5u %5u %10lu %10lu %10lu\n", i,
>> + class->size, obj_allocated, obj_used, pages_used);
>> +
>> + total_objs += obj_allocated;
>> + total_used_objs += obj_used;
>> + total_pages += pages_used;
>> + }
>> +
>> + seq_puts(s, "\n");
>> + seq_printf(s, " %5s %5s %10lu %10lu %10lu\n", "Total", "",
>> + total_objs, total_used_objs, total_pages);
>> +
>> + return 0;
>> +}
>>
>> ...
>>
>> +static int zs_pool_stat_create(struct zs_pool *pool)
>> +{
>> + char name[10];
>
> This is not good. If the kernel creates and then destroys a pool 10000
> times, zs_pool_index==10000 and we overrun the buffer. Could use
> kasprintf() in here to fix this.
Yes, kasprintf() is better. Although I used snprintf().
I will change it.
>
> zs_pool_index isn't a very good name - it doesn't index anything.
> zs_pool_id would be better.
Okay.
>
>> + struct dentry *entry;
>> +
>> + if (!zs_stat_root)
>> + return -ENODEV;
>> +
>> + pool->index = atomic_inc_return(&zs_pool_index);
>> + snprintf(name, sizeof(name), "pool-%d", pool->index);
>> + entry = debugfs_create_dir(name, zs_stat_root);
>> + if (!entry) {
>> + pr_warn("pool %d, debugfs dir <%s> creation failed\n",
>> + pool->index, name);
>> + return -ENOMEM;
>
> Sigh. The debugfs interface does suck. Doesn't matter much.
>
>> + }
>> + pool->stat_dentry = entry;
>> +
>> + entry = debugfs_create_file("obj_in_classes", S_IFREG | S_IRUGO,
>> + pool->stat_dentry, pool, &zs_stat_size_ops);
>> + if (!entry) {
>> + pr_warn("pool %d, debugfs file entry <%s> creation failed\n",
>> + pool->index, "obj_in_classes");
>> + return -ENOMEM;
>> + }
>> +
>> + return 0;
>> +}
>>
>> ...
>>
>
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