On Tue, Sep 25, 2018 at 1:37 PM, Joel Fernandes [off-list ref] wrote:

On Sun, Sep 23, 2018 at 8:33 AM, Sai Prakash Ranjan
[off-list ref] wrote:

quoted

On 9/22/2018 10:07 PM, Sai Prakash Ranjan wrote:

quoted

On 9/22/2018 2:35 PM, Joel Fernandes wrote:

quoted

On Sat, Sep 8, 2018 at 4:28 PM Sai Prakash Ranjan
[off-list ref] wrote:

quoted

+
+       trace_seq_init(&iter->seq);
+       iter->ent = fbuffer->entry;
+       event_call->event.funcs->trace(iter, 0, event);
+       trace_seq_putc(&iter->seq, 0);

Would it be possible to store the binary trace record in the pstore
buffer instead of outputting text? I suspect that will both be faster
and less space.

I will try this and come back.

Hi Joel,

I removed trace_seq_putc and there is some improvement seen: 203 MB/s

# dd if=/dev/zero of=/dev/null status=progress
12207371264 bytes (12 GB, 11 GiB) copied, 60 s, 203 MB/s^C
24171926+0 records in
24171926+0 records out
12376026112 bytes (12 GB, 12 GiB) copied, 60.8282 s, 203 MB/s

This seems good when compared to 190 MB/s seen previously.
If this is Ok, then I will spin v2 with changes suggested.

Sorry for slow reply, yes that sounds good and a worthwhile perf improvement.

Well so I think you should still not use spinlock to synchronize and
split the buffer. You could expand pstore_record to have a ts field or
introduce a new API like ->write_percpu instead of write, or
something. But I strongly feel you should lock. For ftrace function
trace, the perf reduction with locking was dramatic.

- Joel