Re: [PATCH 10/15] drm/i915: Enable GuC firmware log

Chris Wilson
2015-06-16T11:41:02Z

On Tue, Jun 16, 2015 at 10:26:40AM +0100, Tvrtko Ursulin wrote:
>
> On 06/15/2015 07:36 PM, Dave Gordon wrote:
> >From: Alex Dai <yu.dai@intel.com>
> >
> >Allocate a GEM object to hold GuC log data. A debugfs interface
> >(i915_guc_log_dump) is provided to print out the log content.
> >
> >Issue: VIZ-4884
> >Signed-off-by: Alex Dai <yu.dai@intel.com>
> >Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
> >---
> > drivers/gpu/drm/i915/i915_debugfs.c | 29 +++++++++++++++++++
> > drivers/gpu/drm/i915/i915_guc_submission.c | 43 ++++++++++++++++++++++++++++
> > 2 files changed, 72 insertions(+)
> >
> >diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> >index c52a745..b0aa4af 100644
> >--- a/drivers/gpu/drm/i915/i915_debugfs.c
> >+++ b/drivers/gpu/drm/i915/i915_debugfs.c
> >@@ -2388,6 +2388,34 @@ static int i915_guc_load_status_info(struct seq_file *m, void *data)
> > return 0;
> > }
> >
> >+static int i915_guc_log_dump(struct seq_file *m, void *data)
> >+{
> >+ struct drm_info_node *node = m->private;
> >+ struct drm_device *dev = node->minor->dev;
> >+ struct drm_i915_private *dev_priv = dev->dev_private;
> >+ struct drm_i915_gem_object *log_obj = dev_priv->guc.log_obj;
> >+ u32 *log;
> >+ int i = 0, pg;
> >+
> >+ if (!log_obj)
> >+ return 0;
> >+
> >+ for (pg = 0; pg < log_obj->base.size / PAGE_SIZE; pg++) {
> >+ log = kmap_atomic(i915_gem_object_get_page(log_obj, pg));
> >+
> >+ for (i = 0; i < PAGE_SIZE / sizeof(u32); i += 4)
> >+ seq_printf(m, "0x%08x 0x%08x 0x%08x 0x%08x\n",
> >+ *(log + i), *(log + i + 1),
> >+ *(log + i + 2), *(log + i + 3));
> >+
> >+ kunmap_atomic(log);
> >+ }
>
> This doesn't look performance critical, but you could also use
> sg_miter_ family of functions/macros to iterate and kmap sg list
> pages. I did not bother figuring out what kind of smarts
> i915_gem_object_get_page does, but it is not likely it can beat
> sg_miter_ for efficiency.

It does. I have patches to replace more uses of sg_page_iter because it
is the slow point in many functions.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre