On Tue, Mar 22, 2022 at 01:36:26PM -0700, Casey Schaufler wrote: > On 3/22/2022 12:27 PM, Miklos Szeredi wrote: > > Add a new userspace API that allows getting multiple short values in a > > single syscall. > > > > This would be useful for the following reasons: > > > > - Calling open/read/close for many small files is inefficient. E.g. on my > > desktop invoking lsof(1) results in ~60k open + read + close calls under > > /proc and 90% of those are 128 bytes or less. > > You don't need the generality below to address this issue. > > int openandread(const char *path, char *buffer, size_t size); > > would address this case swimmingly. Or you can use my readfile(2) proposal: https://lore.kernel.org/r/20200704140250.423345-1-gregkh@xxxxxxxxxxxxxxxxxxx But you had better actually benchmark the thing. Turns out that I could not find a real-world use that shows improvements in anything. Miklos, what userspace tool will use this new syscall and how will it be faster than readfile() was? I should rebase that against 5.17 again and see if anything is different due to the new spectre-bhb slowdowns. thanks, greg k-h
