Re: [PATCH v3 00/13] xen: drop hypercall function tables

[Juergen Gross <jgross@suse.com>]

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On 13.12.21 11:35, Jan Beulich wrote:
> On 09.12.2021 10:10, Juergen Gross wrote:
>> On 09.12.21 10:05, Jan Beulich wrote:
>>> On 08.12.2021 16:55, Juergen Gross wrote:
>>>> In order to avoid indirect function calls on the hypercall path as
>>>> much as possible this series is removing the hypercall function tables
>>>> and is replacing the hypercall handler calls via the function array
>>>> by automatically generated call macros.
>>>>
>>>> Another by-product of generating the call macros is the automatic
>>>> generating of the hypercall handler prototypes from the same data base
>>>> which is used to generate the macros.
>>>>
>>>> This has the additional advantage of using type safe calls of the
>>>> handlers and to ensure related handler (e.g. PV and HVM ones) share
>>>> the same prototypes.
>>>>
>>>> A very brief performance test (parallel build of the Xen hypervisor
>>>> in a 6 vcpu guest) showed a very slim improvement (less than 1%) of
>>>> the performance with the patches applied. The test was performed using
>>>> a PV and a PVH guest.
>>>>
>>>> Changes in V2:
>>>> - new patches 6, 14, 15
>>>> - patch 7: support hypercall priorities for faster code
>>>> - comments addressed
>>>>
>>>> Changes in V3:
>>>> - patches 1 and 4 removed as already applied
>>>> - comments addressed
>>>>
>>>> Juergen Gross (13):
>>>>     xen: move do_vcpu_op() to arch specific code
>>>>     xen: harmonize return types of hypercall handlers
>>>>     xen: don't include asm/hypercall.h from C sources
>>>>     xen: include compat/platform.h from hypercall.h
>>>>     xen: generate hypercall interface related code
>>>>     xen: use generated prototypes for hypercall handlers
>>>>     x86/pv-shim: don't modify hypercall table
>>>>     xen/x86: don't use hypercall table for calling compat hypercalls
>>>>     xen/x86: call hypercall handlers via generated macro
>>>>     xen/arm: call hypercall handlers via generated macro
>>>>     xen/x86: add hypercall performance counters for hvm, correct pv
>>>>     xen: drop calls_to_multicall performance counter
>>>>     tools/xenperf: update hypercall names
>>>
>>> It's not easy to tell which, if any, of the later patches are fully
>>> independent of earlier ones and could go in ahead of those awaiting
>>> further acks. Do you have any suggestion there, or should we wait
>>> until things can be applied in order?
>>
>> I think all but the last patch should be applied in order. The last one
>> obviously can be applied at any time.
> 
> Hmm, I think 11 and 12 are fine to go ahead as well; I actually need them
> for some immediate purpose and hence I did pull them (but nothing else)
> into my local tree, without observing issues.

Yeah, those should be okay to take.


Juergen


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