Messages in this thread | | | Date | Thu, 29 May 2014 23:08:28 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH V2 1/2] ftrace: Make saved_cmdlines use seq_read |
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On Thu, 20 Feb 2014 17:44:31 +0900 Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> wrote:
> Current tracing_saved_cmdlines_read() implementation is naive; > simply allocate a big buffer, construct output data on the > buffer for each read operation, and then copy a portion of > the buffer to the user space buffer. This can cause a couple of > issues such as a slow memory allocation, high cpu usage, and a > corruption of the output data. > > To address these issues, make saved_cmdlines use seq_read.
I changed the subject and change log to the following. The patch is untouched:
tracing: Have saved_cmdlines use the seq_read infrastructure
Current tracing_saved_cmdlines_read() implementation is naive; It allocates a large buffer, constructs output data to that buffer for each read operation, and then copies a portion of the buffer to the user space buffer. This has several issues such as slow memory allocation, high CPU usage, and even corruption of the output data.
The seq_read infrastructure is made to handle this type of work. By converting it to use seq_read() the code becomes smaller, simplified, as well as correct.
-- Steve
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