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SubjectRe: [PATCH] cma:tracing: Print alloc result in trace_cma_alloc_finish
On Thu, 8 Dec 2022 22:21:30 +0800
Wenchao Hao <haowenchao@huawei.com> wrote:

> The result of allocation is not printed in trace_cma_alloc_finish
> now, while it's important to do it so we can set filters to catch
> specific error on allocation or trigger some operations on specific
> error.
>
> Although we have printed the result in log, but the log is
> conditional and could not be filtered by tracing event.
>
> What's more, it introduce little overhead to print this result.
> The result of allocation is named as errorno in trace.

This looks good to me. BTW, with this change, cma_alloc_class has only
one event - cma_alloc_busy_retry. If so, can we remove the cma_alloc_class?

Thank you,

>
> Signed-off-by: Wenchao Hao <haowenchao@huawei.com>
> ---
> include/trace/events/cma.h | 32 +++++++++++++++++++++++++++++---
> mm/cma.c | 2 +-
> 2 files changed, 30 insertions(+), 4 deletions(-)
>
> diff --git a/include/trace/events/cma.h b/include/trace/events/cma.h
> index 3d708dae1542..ef75ea606ab2 100644
> --- a/include/trace/events/cma.h
> +++ b/include/trace/events/cma.h
> @@ -91,12 +91,38 @@ TRACE_EVENT(cma_alloc_start,
> __entry->align)
> );
>
> -DEFINE_EVENT(cma_alloc_class, cma_alloc_finish,
> +TRACE_EVENT(cma_alloc_finish,
>
> TP_PROTO(const char *name, unsigned long pfn, const struct page *page,
> - unsigned long count, unsigned int align),
> + unsigned long count, unsigned int align, int errorno),
>
> - TP_ARGS(name, pfn, page, count, align)
> + TP_ARGS(name, pfn, page, count, align, errorno),
> +
> + TP_STRUCT__entry(
> + __string(name, name)
> + __field(unsigned long, pfn)
> + __field(const struct page *, page)
> + __field(unsigned long, count)
> + __field(unsigned int, align)
> + __field(int, errorno)
> + ),
> +
> + TP_fast_assign(
> + __assign_str(name, name);
> + __entry->pfn = pfn;
> + __entry->page = page;
> + __entry->count = count;
> + __entry->align = align;
> + __entry->errorno = errorno;
> + ),
> +
> + TP_printk("name=%s pfn=0x%lx page=%p count=%lu align=%u errorno=%d",
> + __get_str(name),
> + __entry->pfn,
> + __entry->page,
> + __entry->count,
> + __entry->align,
> + __entry->errorno)
> );
>
> DEFINE_EVENT(cma_alloc_class, cma_alloc_busy_retry,
> diff --git a/mm/cma.c b/mm/cma.c
> index 4a978e09547a..a75b17b03b66 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -491,7 +491,7 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
> start = bitmap_no + mask + 1;
> }
>
> - trace_cma_alloc_finish(cma->name, pfn, page, count, align);
> + trace_cma_alloc_finish(cma->name, pfn, page, count, align, ret);
>
> /*
> * CMA can allocate multiple page blocks, which results in different
> --
> 2.32.0
>


--
Masami Hiramatsu (Google) <mhiramat@kernel.org>

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