intel-gfx.lists.freedesktop.org archive mirror
 help / color / mirror / Atom feed
From: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx <Intel-gfx@lists.freedesktop.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Tvrtko Ursulin <tvrtko.ursulin@intel.com>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Matthew Auld <matthew.auld@intel.com>,
	Eero Tamminen <eero.t.tamminen@intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: Re: [Intel-gfx] [PATCH 2/2] drm/i915: Use Transparent Hugepages when IOMMU is enabled
Date: Fri, 3 Sep 2021 13:47:52 +0100	[thread overview]
Message-ID: <c8aecd1e-f6d6-cec2-3352-e01c9427248b@linux.intel.com> (raw)
In-Reply-To: <CAKMK7uE412nf5RisGBR2GrNsvgPH+omHv4K+m5McJv1t55DQMQ@mail.gmail.com>


On 29/07/2021 15:06, Daniel Vetter wrote:
> On Thu, Jul 29, 2021 at 3:34 PM Tvrtko Ursulin
> <tvrtko.ursulin@linux.intel.com> wrote:
>>
>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>
>> Usage of Transparent Hugepages was disabled in 9987da4b5dcf
>> ("drm/i915: Disable THP until we have a GPU read BW W/A"), but since it
>> appears majority of performance regressions reported with an enabled IOMMU
>> can be almost eliminated by turning them on, lets just do that.
>>
>> To err on the side of safety we keep the current default in cases where
>> IOMMU is not active, and only when it is default to the "huge=within_size"
>> mode. Although there probably would be wins to enable them throughout,
>> more extensive testing across benchmarks and platforms would need to be
>> done.
>>
>> With the patch and IOMMU enabled my local testing on a small Skylake part
>> shows OglVSTangent regression being reduced from ~14% (IOMMU on versus
>> IOMMU off) to ~2% (same comparison but with THP on).
>>
>> v2:
>>   * Add Kconfig dependency to transparent hugepages and some help text.
>>   * Move to helper for easier handling of kernel build options.
>>
>> v3:
>>   * Drop Kconfig. (Daniel)
>>
>> References: b901bb89324a ("drm/i915/gemfs: enable THP")
>> References: 9987da4b5dcf ("drm/i915: Disable THP until we have a GPU read BW W/A")
>> References: https://gitlab.freedesktop.org/drm/intel/-/issues/430
>> Co-developed-by: Chris Wilson <chris@chris-wilson.co.uk>
>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
>> Cc: Matthew Auld <matthew.auld@intel.com>
>> Cc: Eero Tamminen <eero.t.tamminen@intel.com>
>> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>> Cc: Daniel Vetter <daniel@ffwll.ch>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com> # v1
> 
> On both patches: Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Eero's testing results at 
https://gitlab.freedesktop.org/drm/intel/-/issues/430 are looking good - 
seem to show this to be a net win for at least Gen9 and Gen12 platforms.

Is the ack enough to merge in this case or I should look for an r-b as well?

Regards,

Tvrtko

>> ---
>>   drivers/gpu/drm/i915/gem/i915_gemfs.c | 22 +++++++++++++++++++---
>>   1 file changed, 19 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gemfs.c b/drivers/gpu/drm/i915/gem/i915_gemfs.c
>> index 5e6e8c91ab38..dbdbdc344d87 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gemfs.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gemfs.c
>> @@ -6,7 +6,6 @@
>>
>>   #include <linux/fs.h>
>>   #include <linux/mount.h>
>> -#include <linux/pagemap.h>
>>
>>   #include "i915_drv.h"
>>   #include "i915_gemfs.h"
>> @@ -15,6 +14,7 @@ int i915_gemfs_init(struct drm_i915_private *i915)
>>   {
>>          struct file_system_type *type;
>>          struct vfsmount *gemfs;
>> +       char *opts;
>>
>>          type = get_fs_type("tmpfs");
>>          if (!type)
>> @@ -26,10 +26,26 @@ int i915_gemfs_init(struct drm_i915_private *i915)
>>           *
>>           * One example, although it is probably better with a per-file
>>           * control, is selecting huge page allocations ("huge=within_size").
>> -        * Currently unused due to bandwidth issues (slow reads) on Broadwell+.
>> +        * However, we only do so to offset the overhead of iommu lookups
>> +        * due to bandwidth issues (slow reads) on Broadwell+.
>>           */
>>
>> -       gemfs = kern_mount(type);
>> +       opts = NULL;
>> +       if (intel_vtd_active()) {
>> +               if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
>> +                       static char huge_opt[] = "huge=within_size"; /* r/w */
>> +
>> +                       opts = huge_opt;
>> +                       drm_info(&i915->drm,
>> +                                "Transparent Hugepage mode '%s'\n",
>> +                                opts);
>> +               } else {
>> +                       drm_notice(&i915->drm,
>> +                                  "Transparent Hugepage support is recommended for optimal performance when IOMMU is enabled!\n");
>> +               }
>> +       }
>> +
>> +       gemfs = vfs_kern_mount(type, SB_KERNMOUNT, type->name, opts);
>>          if (IS_ERR(gemfs))
>>                  return PTR_ERR(gemfs);
>>
>> --
>> 2.30.2
>>
> 
> 

  reply	other threads:[~2021-09-03 12:48 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-29 13:34 [Intel-gfx] [PATCH 1/2] drm/i915/selftests: fixup igt_shrink_thp Tvrtko Ursulin
2021-07-29 13:34 ` [Intel-gfx] [PATCH 2/2] drm/i915: Use Transparent Hugepages when IOMMU is enabled Tvrtko Ursulin
2021-07-29 14:06   ` Daniel Vetter
2021-09-03 12:47     ` Tvrtko Ursulin [this message]
2021-09-07  8:42       ` Daniel Vetter
2021-09-07  9:34         ` Tvrtko Ursulin
2021-07-29 14:01 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [1/2] drm/i915/selftests: fixup igt_shrink_thp Patchwork
2021-07-29 14:29 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-07-29 23:16 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
  -- strict thread matches above, loose matches on Subject: below --
2021-07-29 11:18 [Intel-gfx] [PATCH 1/2] " Tvrtko Ursulin
2021-07-29 11:18 ` [Intel-gfx] [PATCH 2/2] drm/i915: Use Transparent Hugepages when IOMMU is enabled Tvrtko Ursulin
2021-07-29 12:07   ` Daniel Vetter
2021-07-29 12:21     ` Tvrtko Ursulin
2021-07-29 12:28       ` Daniel Vetter

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=c8aecd1e-f6d6-cec2-3352-e01c9427248b@linux.intel.com \
    --to=tvrtko.ursulin@linux.intel.com \
    --cc=Intel-gfx@lists.freedesktop.org \
    --cc=chris@chris-wilson.co.uk \
    --cc=daniel@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=eero.t.tamminen@intel.com \
    --cc=joonas.lahtinen@linux.intel.com \
    --cc=matthew.auld@intel.com \
    --cc=rodrigo.vivi@intel.com \
    --cc=tvrtko.ursulin@intel.com \
    --subject='Re: [Intel-gfx] [PATCH 2/2] drm/i915: Use Transparent Hugepages when IOMMU is enabled' \
    /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

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).