On 10/17/2016 09:39 AM, SF Markus Elfring wrote: >>>> Does it improve code? Does it improve anything? >>> >>> Yes. - I got such an impression. >>> >>> * Is it more efficient to call the function "seq_printf" for the desired data processing >>> for a single character than to pass it to the function "" in a string? >>> >>> * Will the required data transfer shrink a bit for the affected functions because of >>> such a change? >>> >> Which are questions _you_ should be able to answer. > > I wonder that the answers are not obvious for you already. > > Calling the function "seq_putc" will be more efficient than "seq_printf" > in this case because of the following reasons. > > 1. How does the distribution look like for supported processor architectures > where the data transfer for bytes (as a function call parameter) > is faster than for (string) pointers? > How would I know? I would assume that _you_ did some measurements here; after all, _you_ are trying to push this patch. I could easily claim that seq_printf() is more efficient than seq_putc(), and won't apply your patch. So _you_ have to prove that your patch is more efficient. > 2. Did anybody measure already how many the execution times can vary > for these functions? > Probably not. But referring to the previous topic: Unless _you_ prove that _your_ patch is more efficient it won't get applied. _You_ want us to apply your patch, so the burden is on _you_ to provide the required data. > Where do you get doubts about its efficiency for the data processing > of a single character? > Because it's being called at the end of a function calling seq_printf() already. So exchanging a single call is probably not helping anything, as the compiler will optimize it anyway. Case in point: with your patch the x86_64 compiler generates nearly identical code for driver/md/raid1.c, but with one instruction _more_ after your patch has been applied. So it's not immediately obvious that your patch is an improvement. Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
