From: "wangyanan (Y)" <wangyanan55@huawei.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Andrew Jones <drjones@redhat.com>,
Ben Gardon <bgardon@google.com>,
Sean Christopherson <seanjc@google.com>,
Peter Xu <peterx@redhat.com>, <wanghaibin.wang@huawei.com>,
<yuzenghui@huawei.com>, kvm <kvm@vger.kernel.org>,
<linux-kselftest@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 03/10] KVM: selftests: Use flag CLOCK_MONOTONIC_RAW for timing
Date: Mon, 19 Apr 2021 14:40:03 +0800 [thread overview]
Message-ID: <82def592-e36c-25c3-c8c5-84c9be83e926@huawei.com> (raw)
In-Reply-To: <1f892f30-1a72-1bcb-462f-b3d6f2bababb@redhat.com>
Hi Paolo,
On 2021/4/17 21:23, Paolo Bonzini wrote:
> On 30/03/21 10:08, Yanan Wang wrote:
>> In addition to function of CLOCK_MONOTONIC, flag CLOCK_MONOTONIC_RAW can
>> also shield possiable impact of NTP, which can provide more robustness.
>>
>> Suggested-by: Vitaly Kuznetsov<vkuznets@redhat.com>
>> Signed-off-by: Yanan Wang<wangyanan55@huawei.com>
>> Reviewed-by: Ben Gardon<bgardon@google.com>
>> Reviewed-by: Andrew Jones<drjones@redhat.com>
>
> I'm not sure about this one, is the effect visible?
>
In practice, difference between results got with CLOCK_MONOTONIC and
CLOCK_MONOTONIC_RAW
actually is too little to be visible. But if just in theory,
CLOCK_MONOTONIC_RAW can ensure time results
of the compared tests are based on the same local oscillator frequency,
which is not subject to possible
NTP frequency adjustment. Change in this patch seems like a bit of
optimization.
But either of these two flags is good to me. If this patch is not
convincing enough to be accepted, I will
post a patch later in fix use of CLOCK_MONOTONIC_RAW in
kvm_page_table_test.c just to be consistent
with other kvm tests, please queue. :）
Thanks,
Yanan
next prev parent reply other threads:[~2021-04-19 6:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 8:08 [PATCH v6 00/10] KVM: selftests: some improvement and a new test for kvm page table Yanan Wang
2021-03-30 8:08 ` [PATCH v6 01/10] tools/headers: sync headers of asm-generic/hugetlb_encode.h Yanan Wang
2021-03-30 8:08 ` [PATCH v6 02/10] mm/hugetlb: Add a macro to get HUGETLB page sizes for mmap Yanan Wang
2021-03-30 8:08 ` [PATCH v6 03/10] KVM: selftests: Use flag CLOCK_MONOTONIC_RAW for timing Yanan Wang
2021-04-17 13:23 ` Paolo Bonzini
2021-04-19 6:40 ` wangyanan (Y) [this message]
2021-04-19 8:22 ` David Laight
2021-04-19 9:33 ` wangyanan (Y)
2021-03-30 8:08 ` [PATCH v6 04/10] KVM: selftests: Print the errno besides error-string in TEST_ASSERT Yanan Wang
2021-03-30 8:08 ` [PATCH v6 05/10] KVM: selftests: Make a generic helper to get vm guest mode strings Yanan Wang
2021-03-30 8:08 ` [PATCH v6 06/10] KVM: selftests: Add a helper to get system configured THP page size Yanan Wang
2021-03-30 8:08 ` [PATCH v6 07/10] KVM: selftests: Add a helper to get system default hugetlb " Yanan Wang
2021-03-30 8:08 ` [PATCH v6 08/10] KVM: selftests: List all hugetlb src types specified with page sizes Yanan Wang
2021-03-30 8:08 ` [PATCH v6 09/10] KVM: selftests: Adapt vm_userspace_mem_region_add to new helpers Yanan Wang
2021-03-30 8:08 ` [PATCH v6 10/10] KVM: selftests: Add a test for kvm page table code Yanan Wang
2021-04-06 3:05 ` [PATCH v6 00/10] KVM: selftests: some improvement and a new test for kvm page table wangyanan (Y)
2021-04-17 13:22 ` Paolo Bonzini
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=82def592-e36c-25c3-c8c5-84c9be83e926@huawei.com \
--to=wangyanan55@huawei.com \
--cc=bgardon@google.com \
--cc=drjones@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=peterx@redhat.com \
--cc=seanjc@google.com \
--cc=vkuznets@redhat.com \
--cc=wanghaibin.wang@huawei.com \
--cc=yuzenghui@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).