Hi, Sorry for late response! On 3/2/2021 6:41 PM, Greg Kroah-Hartman wrote: > On Tue, Mar 02, 2021 at 01:59:46PM +0100, Vlastimil Babka wrote: >> On 2/17/21 7:31 AM, Faiyaz Mohammed wrote: >>> Reading the sys slab alloc_calls, free_calls returns the available object >>> owners, but the size of this file is limited to PAGE_SIZE >>> because of the limitation of sysfs attributes, it is returning the >>> partial owner info, which is not sufficient to debug/account the slab >>> memory and alloc_calls output is not matching with /proc/slabinfo. >>> >>> To remove the PAGE_SIZE limitation converted the sys slab >>> alloc_calls, free_calls to bin attribut >>> >>> Signed-off-by: Faiyaz Mohammed <faiyazm@xxxxxxxxxxxxxx> >> >> After discussing this with Greg and PeterZ, sysfs should be one value per file, >> and is just not proper API for this kind of info. We should reimplement at least >> these clearly debugging "attributes" in debugfs, where they belong, instead of >> trying to hack around the limitation in sysfs. > > sysfs is _REQUIRED_ to be "one value per file", any kernel code that > abuses this needs to be fixed up. > > Why are these slab files in sysfs at all anyway? They all feel like > debugging stuff to me, why not move everything to debugfs? Would make > for a lot less code overall. > Yes, we can move the /sys/kernel/slab/kmemcache/alloc_calls and /sys/kernel/slab/kmemcache/free_calls implementation to debugfs but is it okay to move only alloc_calls and free_calls? or we have to move whole sysfs interface to debugfs?. If we are moving only alloc_calls/free_calls interface to debugfs then I think we can add all slab objects data into single file. For example: /sys/kernel/debugfs/slab/alloc_calls, which will print all slab objects data. Example Output: alloc_list: call_site=__request_region+0xb4/0x2f0 count=228 object_size=128 slab_size=640 slab_name=kmalloc-128 or We can have just like current sysfs interface, have separate alloc_calls/free_calls traces per kmem cache. Which one would be better?. > Thanks and regards, Mohammed Faiyaz
