On Fri, Oct 27, 2023 at 1:27 PM Nhat Pham <nphamcs@xxxxxxxxx> wrote: > > On Tue, Oct 24, 2023 at 7:09 PM Yosry Ahmed <yosryahmed@xxxxxxxxxx> wrote: > > > > On Tue, Oct 24, 2023 at 4:35 PM Nhat Pham <nphamcs@xxxxxxxxx> wrote: > > > > > > During our experiment with zswap, we sometimes observe swap IOs due to > > > occasional zswap store failures and writebacks. These swapping IOs > > > prevent many users who cannot tolerate swapping from adopting zswap to > > > save memory and improve performance where possible. > > > > > > This patch adds the option to bypass swap entirely: do not swap when an > > > zswap store attempt fail, and do not write pages in the zswap pool back > > > to swap. The feature is disabled by default (to preserve the existing > > > behavior), and can be enabled on a cgroup-basis via a new cgroup file. > > > > I think the word "bypass" here is fairly confusing because zswap is > > considered as swap for all purposes, so we are not really bypassing > > swap. I think it should be something like memory.swap.disk or > > memory.swap.writeback or whatever the correct terminology is for > > non-zswap swap (which I honestly don't know). Writing 0 to such an > > interface would give the desired effect. > > I'm honestly not very good at naming things... especially a novel > name that I cannot steal from a precedent... Neither am I :) > > I want something that means "going to zswap is acceptable, but please > don't go to slow swap". Hence, swap bypassing (swap in my mental > model is the slow thing that is under zswap). > > (but I imagined memory.please.don't.go.to.slow.swap won't be very > popular either...) > > memory.swap.disk is... acceptable, I guess? It technically could still be > wrong, as there's still zram, but we can sort of ignore that special case. > I still prefer memory.swap.bypass, but I wouldn't be opposed to this > renaming. > > Anyone with better naming suggestions should absolutely speak up! > Otherwise, I'll send a v2 renaming this to "memory.swap.disk" or > "memory.swap.disk_used" > Hoping someone else chimes in for the naming here, this is not going to be changeable anytime soon.
