Messages in this thread | | | Date | Mon, 17 Oct 2022 13:35:55 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] pstore: migrate to crypto acomp interface (take 2) |
| |
On Mon, Oct 17, 2022 at 10:13:52PM +0200, Ard Biesheuvel wrote: > On Mon, 17 Oct 2022 at 22:11, Kees Cook <keescook@chromium.org> wrote: > > > > On Mon, Oct 17, 2022 at 09:45:08PM +0200, Ard Biesheuvel wrote: > > > On Mon, 17 Oct 2022 at 21:40, Kees Cook <keescook@chromium.org> wrote: > > > > Okay, so strictly speaking, eliminating the per-CPU allocation is an > > > > improvement. Keeping scomp and doing in-place compression will let > > > > pstore use "any" compressions method. > > > > > > I'm not following the point you are making here. > > > > Sorry, I mean to say that if I leave scomp in pstore, nothing is "worse" > > (i.e. the per-cpu allocation is present in both scomp and acomp). i.e. > > no regression either way, but if we switch to a distinct library call, > > it's an improvement on the memory utilization front. > > > > > > Is there a crypto API that does _not_ preallocate the per-CPU stuff? > > > > Because, as you say, it's a huge amount of memory on the bigger > > > > systems... > > > > > > The library interface for each of the respective algorithms. > > > > Where is the crypto API for just using the library interfaces, so I > > don't have to be tied to a specific algo? > > > > That doesn't exist, that is the point.
Shouldn't something like that exist, though?
> But how does the algo matter when you are dealing with mere kilobytes > of ASCII text?
Sure, though, this is how we got here -- every couple of years, someone added another library interface to another compression aglo. I tore all that out so we could avoid having to choose a single one, but was left with the zbufsize mess (that, yes, doesn't matter). So now pstore can just not care what compression is chosen.
-- Kees Cook
| |