Re: staging: lustre: One function call less in class_register_type() after error detection
> This function is called several times during lustre module insert. > Namely it's called 5 times for 5 types: > osc, mdc, lov, lmv, mgc. Will any extra memory accesses matter for the successful execution in this use case? > It's not called any more than that, so it's not exactly a super hot-path > function > to overoptimize it, and the failure is presumed to never happen too > (or the module would be non-functional). Did the assignment for the local variable "rc" with a well-known error code influence the run-time characteristics in unwanted ways? https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/drivers/staging/lustre/lustre/obdclass/genops.c?id=6a5b99a46bedc2cfbba96dec6d255c4b90af9ff8#n140 Regards, Markus
Re: staging: lustre: One function call less in class_register_type() after error detection
On Jul 26, 2016, at 3:56 PM, SF Markus Elfring wrote: >> But kobject_put() already checks for NULL, right? > > Yes. - Such an input parameter validation is performed by the > function implementation. > > >> you just submitted another batch about that in other area. > > I sent update suggestions because of this function property for two > Linux software modules in the year 2015. > > >>> Adjust jump targets according to the Linux coding style convention. >> >> Not that I am totally against this patch, > > Thanks for your feedback. > > >> but when we do not need the extra checks, a single jump target is ok too in >> my mind > > A single goto label will look convenient for a while. It will often work > for several use cases. > > >> (extra benefit - there's not going to be any chance of a mistake to where to >> jump to). > > I have got an other opinion when you would like to care for a bit > more software efficiency. > > >> And when we have a single jump target, there's no supersmart naming >> like free_this_and_that_and_that_other_thing_too. > > How often do you care for efficient exception handling in the shown > function implementations? This function is called several times during lustre module insert. Namely it's called 5 times for 5 types: osc, mdc, lov, lmv, mgc. It's not called any more than that, so it's not exactly a super hot-path function to overoptimize it, and the failure is presumed to never happen too (or the module would be non-functional). I guess you have already did all the work so I don't have any principal objections here, it's just like I said, in a non-super contended path, a single "fail" label is probably easier on the developer when they need to add another check there, as opposed to figuring and possibly adding a correct another label that would do something sensible. Thank you for your contributions.
Re: staging: lustre: One function call less in class_register_type() after error detection
> But kobject_put() already checks for NULL, right? Yes. - Such an input parameter validation is performed by the function implementation. > you just submitted another batch about that in other area. I sent update suggestions because of this function property for two Linux software modules in the year 2015. >> Adjust jump targets according to the Linux coding style convention. > > Not that I am totally against this patch, Thanks for your feedback. > but when we do not need the extra checks, a single jump target is ok too in > my mind A single goto label will look convenient for a while. It will often work for several use cases. > (extra benefit - there's not going to be any chance of a mistake to where to > jump to). I have got an other opinion when you would like to care for a bit more software efficiency. > And when we have a single jump target, there's no supersmart naming > like free_this_and_that_and_that_other_thing_too. How often do you care for efficient exception handling in the shown function implementations? Regards, Markus
