linux-kernel - Re: [PATCH 2/5] KVM: selftests: Remove address rounding in guest code

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Message-ID: <20201102212501.GC20600@xz-x1>
Date:   Mon, 2 Nov 2020 16:25:01 -0500
From:   Peter Xu <peterx@...hat.com>
To:     Ben Gardon <bgardon@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Andrew Jones <drjones@...hat.com>,
        Peter Shier <pshier@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Thomas Huth <thuth@...hat.com>,
        Peter Feiner <pfeiner@...gle.com>
Subject: Re: [PATCH 2/5] KVM: selftests: Remove address rounding in guest code

On Tue, Oct 27, 2020 at 04:37:30PM -0700, Ben Gardon wrote:
> Rounding the address the guest writes to a host page boundary
> will only have an effect if the host page size is larger than the guest
> page size, but in that case the guest write would still go to the same
> host page. There's no reason to round the address down, so remove the
> rounding to simplify the demand paging test.
> 
> This series was tested by running the following invocations on an Intel
> Skylake machine:
> dirty_log_perf_test -b 20m -i 100 -v 64
> dirty_log_perf_test -b 20g -i 5 -v 4
> dirty_log_perf_test -b 4g -i 5 -v 32
> demand_paging_test -b 20m -v 64
> demand_paging_test -b 20g -v 4
> demand_paging_test -b 4g -v 32
> All behaved as expected.
> 
> Signed-off-by: Ben Gardon <bgardon@...gle.com>

Nit: would be better to be before the code movement.  In all cases:

Reviewed-by: Peter Xu <peterx@...hat.com>

-- 
Peter Xu