On 11/23/24 22:35, Shakeel Butt wrote: > On Sat, Nov 23, 2024 at 05:01:57PM +0000, Matthew Wilcox wrote: >> On Fri, Nov 22, 2024 at 10:09:39PM -0800, Shakeel Butt wrote: >> > TP_printk( >> > - "mm=%p memcg_path=%s write=%s", >> > - __entry->mm, >> > - __get_str(memcg_path), >> > + "mm=%p memcg_id=%llu write=%s", >> > + __entry->mm, __entry->memcg_id, >> > __entry->write ? "true" : "false" >> >> Is it actually useful to print out the (hashed) pointer of the mm? >> Wouldn't the PID be more useful so you could actually associate it with >> a task? >> > > For our usecase i.e. bpftrace, we don't really care about these prints > as we can directly access the arguments like mm in bpftrace. I wonder if > others are using this hased pointer in some other way. I don't mind > chaning it but I think that would be a separate patch. I wonder if it's actually hashed when trace events are obtained in binary form, i.e. via trace-cmd. Might be hashed only when doing e.g. cat trace_pipe as that's when the kernel's printk with its hashing is used? I guess that would be another argument for not using it in the tracepoint, as it would be a sidechannel...
