From: John Harrison <John.C.Harrison@Intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, Intel-GFX@Lists.FreeDesktop.Org
Subject: Re: [PATCH 13/13] drm/i915: Cache last IRQ seqno to reduce IRQ overhead
Date: Fri, 11 Dec 2015 15:35:54 +0000 [thread overview]
Message-ID: <566AED5A.2080505@Intel.com> (raw)
In-Reply-To: <20151211145553.GK11596@nuc-i3427.alporthouse.com>
On 11/12/2015 14:55, Chris Wilson wrote:
> On Fri, Dec 11, 2015 at 01:12:01PM +0000, John.C.Harrison@Intel.com wrote:
>> From: John Harrison <John.C.Harrison@Intel.com>
>>
>> The notify function can be called many times without the seqno
>> changing. A large number of duplicates are to prevent races due to the
>> requirement of not enabling interrupts until requested. However, when
>> interrupts are enabled the IRQ handle can be called multiple times
>> without the ring's seqno value changing. This patch reduces the
>> overhead of these extra calls by caching the last processed seqno
>> value and early exiting if it has not changed.
> This is just plain wrong. Every user-interrupt is preceded by a seqno
> update.
Except that mutiple interrupts can be coalesced if they occur too close
together. The driver's IRQ handler still gets called for each individual
interrupt but the first time it is run it sees the seqno for the last.
Thus all the processing gets done on the first invocation. The multiple
subsequent invocations (I have seen up to four I believe) then have
nothing to do.
> -Chris
>
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2015-12-11 15:35 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-11 13:11 [PATCH 00/13] Convert requests to use struct fence John.C.Harrison
2015-12-11 13:11 ` [PATCH 01/13] staging/android/sync: Support sync points created from dma-fences John.C.Harrison
2015-12-17 17:32 ` [Intel-gfx] " Jesse Barnes
2015-12-11 13:11 ` [PATCH 02/13] staging/android/sync: add sync_fence_create_dma John.C.Harrison
2015-12-17 17:29 ` Jesse Barnes
2015-12-11 13:11 ` [PATCH 03/13] staging/android/sync: Move sync framework out of staging John.C.Harrison
2015-12-17 17:35 ` Jesse Barnes
2015-12-21 10:03 ` Daniel Vetter
2015-12-21 14:20 ` John Harrison
2015-12-21 15:46 ` Daniel Vetter
2015-12-22 12:14 ` John Harrison
2015-12-11 13:11 ` [PATCH 04/13] android/sync: Improved debug dump to dmesg John.C.Harrison
2015-12-17 17:36 ` Jesse Barnes
2015-12-11 13:11 ` [PATCH 05/13] drm/i915: Convert requests to use struct fence John.C.Harrison
2015-12-17 17:43 ` Jesse Barnes
2016-01-04 17:20 ` Jesse Barnes
2016-01-04 20:57 ` Chris Wilson
2016-01-04 21:16 ` Jesse Barnes
2016-01-08 21:47 ` Chris Wilson
2016-01-08 21:55 ` Jesse Barnes
2015-12-11 13:11 ` [PATCH 06/13] drm/i915: Removed now redudant parameter to i915_gem_request_completed() John.C.Harrison
2015-12-11 13:11 ` [PATCH 07/13] drm/i915: Add per context timelines to fence object John.C.Harrison
2015-12-17 17:49 ` Jesse Barnes
2015-12-21 10:16 ` Chris Wilson
2015-12-11 13:11 ` [PATCH 08/13] drm/i915: Delay the freeing of requests until retire time John.C.Harrison
2015-12-11 13:11 ` [PATCH 09/13] drm/i915: Interrupt driven fences John.C.Harrison
2015-12-11 15:30 ` John Harrison
2015-12-11 16:07 ` Tvrtko Ursulin
2015-12-11 13:11 ` [PATCH 10/13] drm/i915: Updated request structure tracing John.C.Harrison
2015-12-11 13:11 ` [PATCH 11/13] android/sync: Fix reversed sense of signaled fence John.C.Harrison
2015-12-11 15:57 ` Tvrtko Ursulin
2015-12-14 11:22 ` John Harrison
2015-12-14 12:37 ` Tvrtko Ursulin
2015-12-11 13:12 ` [PATCH 12/13] drm/i915: Add sync framework support to execbuff IOCTL John.C.Harrison
2015-12-11 15:29 ` Tvrtko Ursulin
2015-12-14 11:46 ` John Harrison
2015-12-14 12:23 ` Chris Wilson
2015-12-11 13:12 ` [PATCH 13/13] drm/i915: Cache last IRQ seqno to reduce IRQ overhead John.C.Harrison
2015-12-11 14:28 ` Tvrtko Ursulin
2015-12-14 11:58 ` John Harrison
2015-12-14 12:52 ` Tvrtko Ursulin
2015-12-11 14:55 ` Chris Wilson
2015-12-11 15:35 ` John Harrison [this message]
2015-12-11 16:07 ` Chris Wilson
2016-01-08 18:47 ` [PATCH 0/7] Convert requests to use struct fence John.C.Harrison
2016-01-08 18:47 ` [PATCH 1/7] drm/i915: " John.C.Harrison
2016-01-08 21:59 ` Chris Wilson
2016-01-11 19:03 ` John Harrison
2016-01-11 22:41 ` Jesse Barnes
2016-01-08 18:47 ` [PATCH 2/7] drm/i915: Removed now redudant parameter to i915_gem_request_completed() John.C.Harrison
2016-01-11 22:43 ` Jesse Barnes
2016-01-08 18:47 ` [PATCH 3/7] drm/i915: Add per context timelines to fence object John.C.Harrison
2016-01-08 22:05 ` Chris Wilson
2016-01-11 19:03 ` John Harrison
2016-01-11 22:47 ` Jesse Barnes
2016-01-11 22:58 ` Chris Wilson
2016-01-12 11:03 ` John Harrison
2016-01-12 11:26 ` Chris Wilson
2016-01-08 18:47 ` [PATCH 4/7] drm/i915: Delay the freeing of requests until retire time John.C.Harrison
2016-01-08 22:08 ` Chris Wilson
2016-01-11 19:06 ` John Harrison
2016-01-25 11:52 ` Maarten Lankhorst
2016-01-25 12:11 ` Chris Wilson
2016-01-08 18:47 ` [PATCH 5/7] drm/i915: Interrupt driven fences John.C.Harrison
2016-01-08 22:14 ` Chris Wilson
2016-01-09 0:30 ` Chris Wilson
2016-01-08 22:46 ` Chris Wilson
2016-01-11 19:10 ` John Harrison
2016-01-11 23:01 ` Jesse Barnes
2016-01-08 18:47 ` [PATCH 6/7] drm/i915: Updated request structure tracing John.C.Harrison
2016-01-08 22:16 ` Chris Wilson
2016-01-08 18:47 ` [PATCH 7/7] drm/i915: Cache last IRQ seqno to reduce IRQ overhead John.C.Harrison
2016-01-08 22:47 ` [PATCH 0/7] Convert requests to use struct fence Chris Wilson
2016-01-11 19:15 ` John Harrison
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=566AED5A.2080505@Intel.com \
--to=john.c.harrison@intel.com \
--cc=Intel-GFX@Lists.FreeDesktop.Org \
--cc=chris@chris-wilson.co.uk \
/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).