All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Sebastian Schütte" <dracon@ewetel.net>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: KVM list <kvm@vger.kernel.org>
Subject: Re: [Bug 103321] New: NPT page attribute support causes extreme slowdown
Date: Wed, 2 Sep 2015 21:01:25 +0200	[thread overview]
Message-ID: <55E74785.2060701@ewetel.net> (raw)
In-Reply-To: <55DA8054.7080900@redhat.com>

I inserted some printk() lines into init_vmcb() around the call of svm_set_guest_pat() to print out the g_pat value as well as svm->vcpu.vcpu_id and noticed that something was off:

Initially, the PATs of all VCPUs are set to 0x0606060606060606. However, after attaching some devices (vfio-pci enabling device and vfio_ecap_init lines are being printed) init_vmcb() is only called again for vcpu_id > 0. Unless g_pat is changed somewhere else, VCPU #0 remains set to 0x0606060606060606 (according to comments in svm_set_guest_pat() this is bad for assigned devices) while all other VCPUs use 0x0007040600070406.

I'd guess that could explain the slowdown.


  parent reply	other threads:[~2015-09-02 19:01 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-22 22:16 [Bug 103321] New: NPT page attribute support causes extreme slowdown bugzilla-daemon
2015-08-22 22:16 ` [Bug 103321] " bugzilla-daemon
2015-08-22 22:17 ` bugzilla-daemon
     [not found] ` <55D90002.10703@redhat.com>
     [not found]   ` <55DA16BB.4020004@ewetel.net>
2015-08-24  2:24     ` [Bug 103321] New: " Paolo Bonzini
2015-08-24 22:55       ` Sebastian Schütte
2015-09-02 19:01       ` Sebastian Schütte [this message]
2015-09-15 16:32         ` Paolo Bonzini
2015-09-15 20:11           ` Sebastian Schütte
2015-10-28 22:56 ` [Bug 103321] " bugzilla-daemon
2015-10-28 22:56 ` bugzilla-daemon
2015-10-28 23:13 ` bugzilla-daemon
2015-10-28 23:51 ` bugzilla-daemon

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=55E74785.2060701@ewetel.net \
    --to=dracon@ewetel.net \
    --cc=kvm@vger.kernel.org \
    --cc=pbonzini@redhat.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.