On Mon, 6 Dec 2021 22:17:58 +0100 Justin Iurman wrote: > This patch is an attempt to support the buffer occupancy in IOAM trace > data fields. Any feedback is appreciated, or any other idea if this one > is not correct. > > The draft [1] says the following: > > The "buffer occupancy" field is a 4-octet unsigned integer field. > This field indicates the current status of the occupancy of the > common buffer pool used by a set of queues. The units of this field > are implementation specific. Hence, the units are interpreted within > the context of an IOAM-Namespace and/or node-id if used. The authors > acknowledge that in some operational cases there is a need for the > units to be consistent across a packet path through the network, > hence it is recommended for implementations to use standard units > such as Bytes. > > An existing function (i.e., get_slabinfo) is used to retrieve info about > skbuff_head_cache. For that, both the prototype of get_slabinfo and > struct definition of slabinfo were moved from mm/slab.h to > include/linux/slab.h. Any objection on this? > > The function kmem_cache_size is used to retrieve the size of a slab > object. Note that it returns the "object_size" field, not the "size" > field. If needed, a new function (e.g., kmem_cache_full_size) could be > added to return the "size" field. To match the definition from the > draft, the number of bytes is computed as follows: > > slabinfo.active_objs * size > > Thoughts? Implementing the standard is one thing but how useful is this in practice?
