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Date: Wed, 10 Sep 2014 18:20:27 +0400 From: Dmitry Voytik <voytikd@...il.com> To: Al Viro <viro@...iv.linux.org.uk> Cc: Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>, linux-kernel@...r.kernel.org, linux-fsdevel <linux-fsdevel@...r.kernel.org> Subject: Re: [PATCH] fs: seq_file: optimize seq_pad() On Wed, Sep 10, 2014 at 5:21 PM, Al Viro <viro@...iv.linux.org.uk> wrote: > On Wed, Sep 10, 2014 at 01:20:19PM +0400, Dmitry Voytik wrote: >> Use seq_putc() instead of seq_printf() in seq_pad() because the >> former is faster. > > _Solitary_ seq_putc() is certainly going to be faster, but that loop... > Do you have profiling results, or is it just an apriori "printf must > be sloooowwww"? My fail, sorry. The commit message is little bit wrong. I meant that simple looping of seq_putc() is faster than seq_printf(). I haven't done profilings. I just realized that seq_printf() is more complex than simple loop with seq_putc() (no need to decode format string as in vsnprintf(), etc). If I resend the patch with the following commit message: Use a simple loop with seq_putc() instead of seq_printf() in seq_pad() as this approach is faster due to less complexity in terms of machine cycles. Would be it Okay? Thank you for reviewing. -- Best Regards, Dmitry Voytik. voytikd@...il.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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