Re: [linus:master] [iov_iter] c9eec08bac: vm-scalability.throughput -16.9% regression
From: Borislav Petkov
Date: Fri Nov 17 2023 - 14:13:20 EST
On Fri, Nov 17, 2023 at 11:44:10AM -0500, Linus Torvalds wrote:
> So the test robot load is kind of odd.
So looking at that. IINM, its documentation says:
https://git.kernel.org/pub/scm/linux/kernel/git/wfg/vm-scalability.git/tree/Documentation
case-msync:
Create N sparse files, each with a size of $MemTotal. For each sparse file,
start a process to write 1/2N of the sparse file's size. After the write,
do a msync to make sure the change in memory has reached the file.
Is that something userspace usually does?
Some distributed, shared thing logging to the same file?
I obviously have no effing clue what userspace does...
> Not that I think that David's KUnit test is necessarily much of a real
> load either. so...
Which begs the question: what are our priorities here?
I wouldn't want to optimize some weird loads. Especially if you have
weird loads which perform differently depending on what uarch
"optimizations" they sport.
I guess optimizing for the majority of machines - modern FSRM ones which
can do "rep; movsb" just fine - is one way to put it. And the rest is
best effort.
Hmmm.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette