From: David Hildenbrand <david@redhat.com>
To: Shivank Garg <shivankgarg98@gmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, gregkh@linuxfoundation.org,
sergey.senozhatsky@gmail.com, pmladek@suse.com
Subject: Re: Profiling execution time for __alloc_pages_nodemask
Date: Mon, 10 May 2021 17:01:55 +0200 [thread overview]
Message-ID: <03693c3f-e95e-d0a7-d7de-f2cda92ba6ea@redhat.com> (raw)
In-Reply-To: <CAOVCmzGX54u4VLUSLt_yEM4E8MQNLwW4VTkNVurPXbCuQX6d_g@mail.gmail.com>
On 10.05.21 16:57, Shivank Garg wrote:
> Hi Everyone!
>
> I want to profile the time taken to execute the __alloc_pages_nodemask
> for different linux configurations/parameters.
> To measure the execution time, I use the ktime_get() apis. I get the
> ktime_get() on the top, and I want to do ktime_sub(ktime_get(),ktime)
> and record it in a tracepoint.
Don't tracepoints already record a timestamp? It's bee a while since I
worked with tracepoints ...
> However, the patch on implementation prevents the kernel from booting
> up. I debugged the bug to find out that the issue recurs on adding
> ktime_get() inside the __alloc_pages_nodemask path. So, that the
> kernel fails to boot up ( and show the blank screen without any logs )
> I'm using the Linux kernel 5.6.13 (5821a5593fa9f28eb6fcc95c35d00454d9bb8624)
Are you maybe calling ktime_get() too early during boot, where some
subsystems are just about to be brought up?
>
> Is it an expected behavior? or a BUG? Has anyone else faced the same issue?
>
> Can you please suggest, what would be a good way to measure execution
> time for page allocation (if not ktime_get)
I could have sworn ordinary tracepoints would already give you a
timestamp ...
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-05-10 15:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-10 14:57 Profiling execution time for __alloc_pages_nodemask Shivank Garg
2021-05-10 15:01 ` David Hildenbrand [this message]
2021-05-11 0:00 ` Yang Shi
2021-05-11 5:31 ` Shivank Garg
2021-05-12 3:56 ` Yang Shi
2021-05-12 17:39 ` Shivank Garg
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