From: Nathan Lynch <nathanl@linux.ibm.com>
To: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
Cc: Tyrel Datwyler <tyreld@linux.ibm.com>,
linux-kernel@vger.kernel.org,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 3/5] powerpc/pseries: Account for SPURR ticks on idle CPUs
Date: Fri, 21 Feb 2020 10:47:41 -0600 [thread overview]
Message-ID: <87ftf3ubte.fsf@linux.ibm.com> (raw)
In-Reply-To: <1582262314-8319-4-git-send-email-ego@linux.vnet.ibm.com>
"Gautham R. Shenoy" <ego@linux.vnet.ibm.com> writes:
> +static inline void snapshot_spurr_idle_entry(void)
> +{
> + *this_cpu_ptr(&idle_entry_spurr_snap) = mfspr(SPRN_SPURR);
> +}
> +
[...]
> +static inline void update_idle_spurr_accounting(void)
> +{
> + u64 *idle_spurr_cycles_ptr = this_cpu_ptr(&idle_spurr_cycles);
> + u64 in_spurr = *this_cpu_ptr(&idle_entry_spurr_snap);
> +
> + *idle_spurr_cycles_ptr += mfspr(SPRN_SPURR) - in_spurr;
> +}
[...]
> +static inline u64 read_this_idle_spurr(void)
> +{
> + /*
> + * If we are reading from an idle context, update the
> + * idle-spurr cycles corresponding to the last idle period.
> + * Since the idle context is not yet over, take a fresh
> + * snapshot of the idle-spurr.
> + */
> + if (get_lppaca()->idle == 1) {
> + update_idle_spurr_accounting();
> + snapshot_spurr_idle_entry();
This samples spurr twice when it could do with just one. I don't know
the performance implications, but will the results be coherent?
WARNING: multiple messages have this Message-ID (diff)
From: Nathan Lynch <nathanl@linux.ibm.com>
To: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
Michael Ellerman <mpe@ellerman.id.au>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
Tyrel Datwyler <tyreld@linux.ibm.com>
Subject: Re: [PATCH v2 3/5] powerpc/pseries: Account for SPURR ticks on idle CPUs
Date: Fri, 21 Feb 2020 10:47:41 -0600 [thread overview]
Message-ID: <87ftf3ubte.fsf@linux.ibm.com> (raw)
In-Reply-To: <1582262314-8319-4-git-send-email-ego@linux.vnet.ibm.com>
"Gautham R. Shenoy" <ego@linux.vnet.ibm.com> writes:
> +static inline void snapshot_spurr_idle_entry(void)
> +{
> + *this_cpu_ptr(&idle_entry_spurr_snap) = mfspr(SPRN_SPURR);
> +}
> +
[...]
> +static inline void update_idle_spurr_accounting(void)
> +{
> + u64 *idle_spurr_cycles_ptr = this_cpu_ptr(&idle_spurr_cycles);
> + u64 in_spurr = *this_cpu_ptr(&idle_entry_spurr_snap);
> +
> + *idle_spurr_cycles_ptr += mfspr(SPRN_SPURR) - in_spurr;
> +}
[...]
> +static inline u64 read_this_idle_spurr(void)
> +{
> + /*
> + * If we are reading from an idle context, update the
> + * idle-spurr cycles corresponding to the last idle period.
> + * Since the idle context is not yet over, take a fresh
> + * snapshot of the idle-spurr.
> + */
> + if (get_lppaca()->idle == 1) {
> + update_idle_spurr_accounting();
> + snapshot_spurr_idle_entry();
This samples spurr twice when it could do with just one. I don't know
the performance implications, but will the results be coherent?
next prev parent reply other threads:[~2020-02-21 16:49 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 5:18 [PATCH v2 0/5] Track and expose idle PURR and SPURR ticks Gautham R. Shenoy
2020-02-21 5:18 ` Gautham R. Shenoy
2020-02-21 5:18 ` [PATCH v2 1/5] powerpc: Move idle_loop_prolog()/epilog() functions to header file Gautham R. Shenoy
2020-02-21 5:18 ` Gautham R. Shenoy
2020-02-21 15:03 ` Nathan Lynch
2020-02-21 15:03 ` Nathan Lynch
2020-02-24 4:55 ` Gautham R Shenoy
2020-02-24 4:55 ` Gautham R Shenoy
2020-03-06 17:06 ` Nathan Lynch
2020-03-06 17:06 ` Nathan Lynch
2020-02-21 5:18 ` [PATCH v2 2/5] powerpc/idle: Add accessor function to always read latest idle PURR Gautham R. Shenoy
2020-02-21 5:18 ` Gautham R. Shenoy
2020-02-21 5:18 ` [PATCH v2 3/5] powerpc/pseries: Account for SPURR ticks on idle CPUs Gautham R. Shenoy
2020-02-21 5:18 ` Gautham R. Shenoy
2020-02-21 16:47 ` Nathan Lynch [this message]
2020-02-21 16:47 ` Nathan Lynch
2020-02-24 5:05 ` Gautham R Shenoy
2020-02-24 5:05 ` Gautham R Shenoy
2020-02-21 5:18 ` [PATCH v2 4/5] powerpc/sysfs: Show idle_purr and idle_spurr for every CPU Gautham R. Shenoy
2020-02-21 5:18 ` Gautham R. Shenoy
2020-02-21 16:50 ` Nathan Lynch
2020-02-21 16:50 ` Nathan Lynch
2020-02-24 5:14 ` Gautham R Shenoy
2020-02-24 5:14 ` Gautham R Shenoy
2020-02-25 10:20 ` Naveen N. Rao
2020-02-25 10:20 ` Naveen N. Rao
2020-03-06 17:03 ` Nathan Lynch
2020-03-06 17:03 ` Nathan Lynch
2020-03-06 17:35 ` Naveen N. Rao
2020-03-06 17:35 ` Naveen N. Rao
2020-02-21 5:18 ` [PATCH v2 5/5] Documentation: Document sysfs interfaces purr, spurr, idle_purr, idle_spurr Gautham R. Shenoy
2020-02-21 5:18 ` Gautham R. Shenoy
2020-02-21 16:55 ` Nathan Lynch
2020-02-21 16:55 ` Nathan Lynch
2020-02-24 5:15 ` Gautham R Shenoy
2020-02-24 5:15 ` Gautham R Shenoy
2020-02-24 4:17 ` [PATCH v2 0/5] Track and expose idle PURR and SPURR ticks Kamalesh Babulal
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=87ftf3ubte.fsf@linux.ibm.com \
--to=nathanl@linux.ibm.com \
--cc=ego@linux.vnet.ibm.com \
--cc=kamalesh@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=naveen.n.rao@linux.vnet.ibm.com \
--cc=svaidy@linux.vnet.ibm.com \
--cc=tyreld@linux.ibm.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.