Re: [PATCH 5/7] ramoops: Split ftrace buffer space into per-CPU zones

From: Joel Fernandes
Date: Sun Oct 09 2016 - 13:15:28 EST


On Fri, Oct 7, 2016 at 10:28 PM, Joel Fernandes <joelaf@xxxxxxxxxx> wrote:
> If FTRACE_PER_CPU flag is passed to ramoops pdata, split the space into
> multiple zones depending on the number of CPUs.
>
> This speeds up the performance of function tracing by about 280% in my tests as
> we avoid the locking. The trade off being lesser space available per CPU. Let
> the ramoops user decide which option they want based on pdata flag.
>
> Signed-off-by: Joel Fernandes <joelaf@xxxxxxxxxx>
> ---
> fs/pstore/ram.c | 70 +++++++++++++++++++++++++++++++++++-----------
> include/linux/pstore_ram.h | 3 ++
> 2 files changed, 56 insertions(+), 17 deletions(-)
>
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
[..]
> @@ -391,14 +418,21 @@ static void ramoops_free_przs(struct ramoops_context *cxt)
> {
> int i;
>
> - if (!cxt->przs)
> - return;
> + /* Free dump PRZs */
> + if (cxt->przs) {
> + for (i = 0; i < cxt->max_dump_cnt; i++)
> + persistent_ram_free(cxt->przs[i]);
>
> - for (i = 0; i < cxt->max_dump_cnt; i++)
> - persistent_ram_free(cxt->przs[i]);
> + kfree(cxt->przs);
> + cxt->max_dump_cnt = 0;
> + }
>
> - kfree(cxt->przs);
> - cxt->max_dump_cnt = 0;
> + /* Free ftrace PRZs */
> + if (cxt->fprzs) {
> + for (i = 0; i < nr_cpu_ids; i++)
> + persistent_ram_free(cxt->przs[i]);

I am supposed to free fprzs[i] here, instead of przs[i]. Also need to
check flag and free correct number of zones. Will fix for v2, sorry
about that.

Thanks,
Joel