From: Dan Williams <dan.j.williams@intel.com>
To: Ira Weiny <ira.weiny@intel.com>, Dan Williams <dan.j.williams@intel.com>
Cc: Alison Schofield <alison.schofield@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Ben Widawsky <bwidawsk@kernel.org>,
"Steven Rostedt" <rostedt@goodmis.org>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Davidlohr Bueso <dave@stgolabs.net>,
"Dave Jiang" <dave.jiang@intel.com>,
<linux-kernel@vger.kernel.org>, <linux-cxl@vger.kernel.org>
Subject: Re: [PATCH V2 03/11] cxl/mem: Implement Clear Event Records command
Date: Fri, 2 Dec 2022 17:14:27 -0800 [thread overview]
Message-ID: <638aa2f3349e_3cbe02943d@dwillia2-xfh.jf.intel.com.notmuch> (raw)
In-Reply-To: <Y4qPAi/DZAyz/Djl@iweiny-desk3>
Ira Weiny wrote:
> On Thu, Dec 01, 2022 at 06:29:20PM -0800, Dan Williams wrote:
> > ira.weiny@ wrote:
> > > From: Ira Weiny <ira.weiny@intel.com>
> > >
> > > CXL rev 3.0 section 8.2.9.2.3 defines the Clear Event Records mailbox
> > > command. After an event record is read it needs to be cleared from the
> > > event log.
> > >
> > > Implement cxl_clear_event_record() to clear all record retrieved from
> > > the device.
> > >
> > > Each record is cleared explicitly. A clear all bit is specified but
> > > events could arrive between a get and any final clear all operation.
> > > This means events would be missed.
> > > Therefore each event is cleared specifically.
> >
> > Note that the spec has a better reason for why Clear All has limited
> > usage:
> >
> > "Clear All Events is only allowed when the Event Log has overflowed;
> > otherwise, the device shall return Invalid Input."
> >
> > Will need to wait and see if we need that to keep pace with a device
> > with a high event frequency.
>
> Perhaps. But yea I would wait and see.
>
> [snip]
>
> > > +static int cxl_clear_event_record(struct cxl_dev_state *cxlds,
> > > + enum cxl_event_log_type log,
> > > + struct cxl_get_event_payload *get_pl,
> > > + u16 total)
> > > +{
> > > + struct cxl_mbox_clear_event_payload payload = {
> > > + .event_log = log,
> > > + };
> > > + int cnt;
> > > +
> > > + /*
> > > + * Clear Event Records uses u8 for the handle cnt while Get Event
> > > + * Record can return up to 0xffff records.
> > > + */
> > > + for (cnt = 0; cnt < total; /* cnt incremented internally */) {
> > > + u8 nr_recs = min_t(u8, (total - cnt),
> > > + CXL_CLEAR_EVENT_MAX_HANDLES);
> >
> > This seems overly complicated. @total is a duplicate of
> > @get_pl->record_count, and the 2 loops feel like it could be cut
> > down to one.
>
> Sure, total is redundant to pass to the function.
>
> However, 2 loops is IMO not at all overly complicated. Note that the 2 loops
> do not do the same thing. The inner loop is filling in the payload for the
> Clear command. There is really no way around doing this.
>
> Now that I've had time to think about it:
>
> Are you suggesting we issue a single mailbox command for every handle?
>
> That would be a single loop. But a lot more mailbox commands.
I was thinking something like this pseudo code
int tosend = le16_to_cpu(get_pl->record_count);
int added = 0;
for (i = 0; i < tosend; i++) {
add_to_clear(added++);
if (added == MAX)
send_mailbox();
added = 0;
}
if (added)
send_mailbox();
...where it batches and sends every 256 and one more send afterwards for
any stragglers.
next prev parent reply other threads:[~2022-12-03 1:14 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-01 0:27 [PATCH V2 00/11] CXL: Process event logs ira.weiny
2022-12-01 0:27 ` [PATCH V2 01/11] cxl/pci: Add generic MSI-X/MSI irq support ira.weiny
2022-12-01 10:18 ` Jonathan Cameron
2022-12-01 18:37 ` Dave Jiang
2022-12-02 0:23 ` Dan Williams
2022-12-02 0:34 ` Ira Weiny
2022-12-02 2:00 ` Dan Williams
2022-12-02 13:04 ` Jonathan Cameron
2022-12-01 0:27 ` [PATCH V2 02/11] cxl/mem: Implement Get Event Records command ira.weiny
2022-12-01 13:06 ` Jonathan Cameron
2022-12-01 15:10 ` Ira Weiny
2022-12-01 17:38 ` Steven Rostedt
2022-12-02 0:09 ` Ira Weiny
2022-12-02 4:40 ` Steven Rostedt
2022-12-02 5:00 ` Steven Rostedt
2022-12-02 21:31 ` Ira Weiny
2022-12-02 1:39 ` Dan Williams
2022-12-02 21:47 ` Ira Weiny
2022-12-03 21:33 ` Dan Williams
2022-12-01 0:27 ` [PATCH V2 03/11] cxl/mem: Implement Clear " ira.weiny
2022-12-01 13:26 ` Jonathan Cameron
2022-12-01 15:30 ` Ira Weiny
2022-12-02 2:29 ` Dan Williams
2022-12-02 13:18 ` Jonathan Cameron
2022-12-02 13:34 ` Steven Rostedt
2022-12-02 19:27 ` Dan Williams
2022-12-02 21:28 ` Ira Weiny
2022-12-02 23:49 ` Ira Weiny
2022-12-03 1:14 ` Dan Williams [this message]
2022-12-06 7:35 ` Ira Weiny
2022-12-01 0:27 ` [PATCH V2 04/11] cxl/mem: Clear events on driver load ira.weiny
2022-12-01 13:30 ` Jonathan Cameron
2022-12-01 17:02 ` Ira Weiny
2022-12-02 2:48 ` Dan Williams
2022-12-02 16:34 ` Ira Weiny
2022-12-02 23:34 ` Dan Williams
2022-12-03 21:00 ` Ira Weiny
2022-12-01 0:27 ` [PATCH V2 05/11] cxl/mem: Trace General Media Event Record ira.weiny
2022-12-01 18:54 ` Dave Jiang
2022-12-02 6:18 ` Dan Williams
2022-12-01 0:27 ` [PATCH V2 06/11] cxl/mem: Trace DRAM " ira.weiny
2022-12-01 18:55 ` Dave Jiang
2022-12-01 0:27 ` [PATCH V2 07/11] cxl/mem: Trace Memory Module " ira.weiny
2022-12-01 13:31 ` Jonathan Cameron
2022-12-01 18:57 ` Dave Jiang
2022-12-02 6:25 ` Dan Williams
2022-12-01 0:27 ` [PATCH V2 08/11] cxl/mem: Wire up event interrupts ira.weiny
2022-12-01 14:21 ` Jonathan Cameron
2022-12-01 17:23 ` Ira Weiny
2022-12-01 18:35 ` Davidlohr Bueso
2022-12-02 7:37 ` Dan Williams
2022-12-02 14:19 ` Jonathan Cameron
2022-12-02 19:43 ` Dan Williams
2022-12-05 13:01 ` Jonathan Cameron
2022-12-05 16:35 ` Dan Williams
2022-12-06 9:38 ` Jonathan Cameron
2022-12-01 0:27 ` [PATCH V2 09/11] cxl/test: Add generic mock events ira.weiny
2022-12-01 14:37 ` Jonathan Cameron
2022-12-01 17:49 ` Ira Weiny
2022-12-02 8:07 ` Dan Williams
2022-12-01 0:27 ` [PATCH V2 10/11] cxl/test: Add specific events ira.weiny
2022-12-01 21:00 ` Dave Jiang
2022-12-01 0:27 ` [PATCH V2 11/11] cxl/test: Simulate event log overflow ira.weiny
2022-12-01 21:28 ` Dave Jiang
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=638aa2f3349e_3cbe02943d@dwillia2-xfh.jf.intel.com.notmuch \
--to=dan.j.williams@intel.com \
--cc=Jonathan.Cameron@huawei.com \
--cc=alison.schofield@intel.com \
--cc=bwidawsk@kernel.org \
--cc=dave.jiang@intel.com \
--cc=dave@stgolabs.net \
--cc=ira.weiny@intel.com \
--cc=linux-cxl@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=vishal.l.verma@intel.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).