From: Steven Rostedt
> Sent: 19 December 2023 18:54
> From: "Tzvetomir Stoyanov (VMware)" <tz.stoya...@gmail.com>
>
> Currently the size of one sub buffer page is global for all buffers and
> it is hard coded to one system page. In order to introduce configurable
> ring buffer sub page size, the internal logic should be refactored to
> work with sub page size per ring buffer.
>
...
> - nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
> + /* Default buffer page size - one system page */
> + buffer->subbuf_size = PAGE_SIZE - BUF_PAGE_HDR_SIZE;
> +
> + /* Max payload is buffer page size - header (8bytes) */
> + buffer->max_data_size = buffer->subbuf_size - (sizeof(u32) * 2);
> +
> + nr_pages = DIV_ROUND_UP(size, buffer->subbuf_size);
While not new, does this really make any sense for systems with 64k pages?
Wouldn't it be better to have units of 4k?
...
> @@ -5102,14 +5110,14 @@ unsigned long ring_buffer_size(struct trace_buffer
> *buffer, int cpu)
> {
> /*
> * Earlier, this method returned
> - * BUF_PAGE_SIZE * buffer->nr_pages
> + * buffer->subbuf_size * buffer->nr_pages
> * Since the nr_pages field is now removed, we have converted this to
> * return the per cpu buffer value.
Overenthusiastic global replace...
David
-
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