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Message-ID: <20090807075317.GC20292@elte.hu>
Date: Fri, 7 Aug 2009 09:53:17 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Mel Gorman <mel@....ul.ie>
Cc: Larry Woodman <lwoodman@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>, riel@...hat.com,
Peter Zijlstra <peterz@...radead.org>,
LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: [PATCH 3/6] tracing, page-allocator: Add trace event for page
traffic related to the buddy lists
* Mel Gorman <mel@....ul.ie> wrote:
> +TRACE_EVENT(mm_page_pcpu_drain,
> +
> + TP_PROTO(struct page *page, int order, int migratetype),
> +
> + TP_ARGS(page, order, migratetype),
> +
> + TP_STRUCT__entry(
> + __field( struct page *, page )
> + __field( int, order )
> + __field( int, migratetype )
> + ),
> +
> + TP_fast_assign(
> + __entry->page = page;
> + __entry->order = order;
> + __entry->migratetype = migratetype;
> + ),
> +
> + TP_printk("page=%p pfn=%lu order=%d cpu=%d migratetype=%d",
> + __entry->page,
> + page_to_pfn(__entry->page),
> + __entry->order,
> + smp_processor_id(),
> + __entry->migratetype)
> + trace_mm_page_alloc_zone_locked(page, order, migratetype, order == 0);
This can be optimized further by omitting the migratetype field and
adding something like this:
TP_printk("page=%p pfn=%lu order=%d cpu=%d migratetype=%d",
__entry->page,
page_to_pfn(__entry->page),
__entry->order,
smp_processor_id(),
__entry->order == 0);
The advantage is 4 bytes less in the record and a shorter tracepoint
fast-path - while still having the same output.
Ingo
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