On Tue, 20 Sep 2022 19:09:15 +0100, Mark Brown <broonie@xxxxxxxxxx> wrote: > > [1 <text/plain; us-ascii (7bit)>] > On Tue, Sep 20, 2022 at 06:14:13PM +0100, Marc Zyngier wrote: > > Mark Brown <broonie@xxxxxxxxxx> wrote: > > > > When we save the state for the floating point registers this can be done > > > in the form visible through either the FPSIMD V registers or the SVE Z and > > > P registers. At present we track which format is currently used based on > > > TIF_SVE and the SME streaming mode state but particularly in the SVE case > > > this limits our options for optimising things, especially around syscalls. > > > Introduce a new enum in thread_struct which explicitly states which format > > > is active and keep it up to date when we change it. > > > > At present we do not use this state except to verify that it has the > > > expected value when loading the state, future patches will introduce > > > functional changes. > > > > + enum fp_state fp_type; > > > Is it a state or a type? Some consistency would help. Also, what does > > We can bikeshed this either way - the state currently stored is > of a particular type. I'll probably go for type. Then please do it consistently. At the moment, this is a bizarre mix of the two, and this is already hard enough to reason about this that we don't need extra complexity! > > > this represent? Your commit message keeps talking about the FP/SVE > > state for the host, but this is obviously a guest-related structure. > > How do the two relate? > > The commit message talks about saving the floating point state in > general which is something we do for both the host and the guest. > The optimisation cases I am focusing on right now are more on > host usage but the complexity with tracking that currently blocks > them crosses both host and guest, indeed the biggest improvement > overall is probably that tracking the guest state stops requiring > us to fiddle with the host task's state which to me at least > makes things clearer. At least for the KVM part, I want a clear comment explaining what this tracks and how this is used, because at the moment, I'm only guessing. And I've had enough guessing with this code... Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
