From: Yan Zhao <yan.y.zhao@intel.com>
To: zhenyuw@linux.intel.com
Cc: alex.williamson@redhat.com, intel-gvt-dev@lists.freedesktop.org,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
pbonzini@redhat.com, kevin.tian@intel.com, peterx@redhat.com,
Yan Zhao <yan.y.zhao@intel.com>
Subject: [PATCH v2 2/2] drm/i915/gvt: subsitute kvm_read/write_guest with vfio_dma_rw
Date: Tue, 14 Jan 2020 22:54:55 -0500 [thread overview]
Message-ID: <20200115035455.12417-1-yan.y.zhao@intel.com> (raw)
In-Reply-To: <20200115034132.2753-1-yan.y.zhao@intel.com>
As a device model, it is better to read/write guest memory using vfio
interface, so that vfio is able to maintain dirty info of device IOVAs.
Compared to kvm interfaces kvm_read/write_guest(), vfio_dma_rw() has ~600
cycles more overhead on average.
-------------------------------------
| interface | avg cpu cycles |
|-----------------------------------|
| kvm_write_guest | 1554 |
| ----------------------------------|
| kvm_read_guest | 707 |
|-----------------------------------|
| vfio_dma_rw(w) | 2274 |
|-----------------------------------|
| vfio_dma_rw(r) | 1378 |
-------------------------------------
Comparison of benchmarks scores are as blow:
------------------------------------------------------
| avg score | kvm_read/write_guest | vfio_dma_rw |
|----------------------------------------------------|
| Glmark2 | 1284 | 1296 |
|----------------------------------------------------|
| Lightsmark | 61.24 | 61.27 |
|----------------------------------------------------|
| OpenArena | 140.9 | 137.4 |
|----------------------------------------------------|
| Heaven | 671 | 670 |
------------------------------------------------------
No obvious performance downgrade found.
Cc: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
---
drivers/gpu/drm/i915/gvt/kvmgt.c | 26 +++++++-------------------
1 file changed, 7 insertions(+), 19 deletions(-)
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index bd79a9718cc7..17edc9a7ff05 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -1966,31 +1966,19 @@ static int kvmgt_rw_gpa(unsigned long handle, unsigned long gpa,
void *buf, unsigned long len, bool write)
{
struct kvmgt_guest_info *info;
- struct kvm *kvm;
- int idx, ret;
- bool kthread = current->mm == NULL;
+ int ret;
+ struct intel_vgpu *vgpu;
+ struct device *dev;
if (!handle_valid(handle))
return -ESRCH;
info = (struct kvmgt_guest_info *)handle;
- kvm = info->kvm;
-
- if (kthread) {
- if (!mmget_not_zero(kvm->mm))
- return -EFAULT;
- use_mm(kvm->mm);
- }
-
- idx = srcu_read_lock(&kvm->srcu);
- ret = write ? kvm_write_guest(kvm, gpa, buf, len) :
- kvm_read_guest(kvm, gpa, buf, len);
- srcu_read_unlock(&kvm->srcu, idx);
+ vgpu = info->vgpu;
+ dev = mdev_dev(vgpu->vdev.mdev);
- if (kthread) {
- unuse_mm(kvm->mm);
- mmput(kvm->mm);
- }
+ ret = write ? vfio_dma_rw(dev, gpa, buf, len, true) :
+ vfio_dma_rw(dev, gpa, buf, len, false);
return ret;
}
--
2.17.1
next prev parent reply other threads:[~2020-01-15 4:04 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-15 3:41 [PATCH v2 0/2] use vfio_dma_rw to read/write IOVAs from CPU side Yan Zhao
2020-01-15 3:53 ` [PATCH v2 1/2] vfio: introduce vfio_dma_rw to read/write a range of IOVAs Yan Zhao
2020-01-15 20:06 ` Alex Williamson
2020-01-16 2:30 ` Mika Penttilä
2020-01-16 2:59 ` Alex Williamson
2020-01-16 3:15 ` Mika Penttilä
2020-01-16 3:58 ` Alex Williamson
2020-01-16 5:32 ` Yan Zhao
2020-01-15 3:54 ` Yan Zhao [this message]
2020-01-15 20:06 ` [PATCH v2 2/2] drm/i915/gvt: subsitute kvm_read/write_guest with vfio_dma_rw Alex Williamson
2020-01-16 5:49 ` Yan Zhao
2020-01-16 15:37 ` Alex Williamson
2020-01-19 10:06 ` Yan Zhao
2020-01-20 20:01 ` Alex Williamson
2020-01-21 8:12 ` Yan Zhao
2020-01-21 16:51 ` Alex Williamson
2020-01-21 22:10 ` Yan Zhao
2020-01-22 3:07 ` Yan Zhao
2020-01-23 10:02 ` Yan Zhao
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=20200115035455.12417-1-yan.y.zhao@intel.com \
--to=yan.y.zhao@intel.com \
--cc=alex.williamson@redhat.com \
--cc=intel-gvt-dev@lists.freedesktop.org \
--cc=kevin.tian@intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=peterx@redhat.com \
--cc=zhenyuw@linux.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).