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Date: Sat, 22 Oct 2016 13:07:36 -0700 From: Joe Perches <joe@...ches.com> To: SF Markus Elfring <elfring@...rs.sourceforge.net>, linux-ia64@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>, Borislav Petkov <bp@...e.de>, Fenghua Yu <fenghua.yu@...el.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Hans-Christian Noren Egtvedt <egtvedt@...fundet.no>, Ingo Molnar <mingo@...nel.org>, Jörg Rödel <jroedel@...e.de>, Krzysztof Kozlowski <krzk@...nel.org>, Robert Richter <rrichter@...ium.com>, Robin Murphy <robin.murphy@....com>, Tony Luck <tony.luck@...el.com>, Toshi Kani <toshi.kani@....com>, Vineet Gupta <vgupta@...opsys.com> Cc: LKML <linux-kernel@...r.kernel.org>, kernel-janitors@...r.kernel.org Subject: Re: [PATCH 6/6] IA64-sn2_smp: Combine two seq_printf() calls into one call in sn2_ptc_seq_show() On Sat, 2016-10-22 at 21:58 +0200, SF Markus Elfring wrote: > Some data were printed into a sequence by two separate function calls. > Print the same data by a single function call instead. [] > diff --git a/arch/ia64/sn/kernel/sn2/sn2_smp.c b/arch/ia64/sn/kernel/sn2/sn2_smp.c [] > @@ -494,12 +494,11 @@ static int sn2_ptc_seq_show(struct seq_file *file, void *data) > int cpu; > > cpu = *(loff_t *) data; > - > - if (!cpu) { > + if (!cpu) > seq_printf(file, > - "# cpu ptc_l newrid ptc_flushes nodes_flushed deadlocks lock_nsec shub_nsec shub_nsec_max not_my_mm deadlock2 ipi_fluches ipi_nsec\n"); > - seq_printf(file, "# ptctest %d, flushopt %d\n", sn2_ptctest, sn2_flush_opt); > - } > + "# cpu ptc_l newrid ptc_flushes nodes_flushed deadlocks lock_nsec shub_nsec shub_nsec_max not_my_mm deadlock2 ipi_fluches ipi_nsec\n" > + "# ptctest %d, flushopt %d\n", > + sn2_ptctest, sn2_flush_opt); > > if (cpu < nr_cpu_ids && cpu_online(cpu)) { > stat = &per_cpu(ptcstats, cpu); Please think more. printf has to inspect character by character looking for a vsprintf % character and 0 termination. seq_puts does a strlen then memcpy. Which is faster? When is it better to call 2 functions? When does readability matter more than efficiency?
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