| Message ID | 20200129121235.1814563-3-anthony.perard@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | OvmfXen: Set PcdFSBClock at runtime | expand |
On 01/29/20 13:12, Anthony PERARD wrote: > We are going to want to change the value of PcdFSBClock at run time in > OvmfXen, so move it to the PcdsDynamic section. > > Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2490 > Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> > --- > CC: Bob Feng <bob.c.feng@intel.com> > CC: Liming Gao <liming.gao@intel.com> > --- > MdePkg/MdePkg.dec | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/MdePkg/MdePkg.dec b/MdePkg/MdePkg.dec > index d022cc5e3ef2..8f5a48346e50 100644 > --- a/MdePkg/MdePkg.dec > +++ b/MdePkg/MdePkg.dec > @@ -2194,10 +2194,6 @@ [PcdsFixedAtBuild,PcdsPatchableInModule] > # @ValidList 0x80000001 | 8, 16, 32 > gEfiMdePkgTokenSpaceGuid.PcdPort80DataWidth|8|UINT8|0x0000002d > > - ## This value is used to configure X86 Processor FSB clock. > - # @Prompt FSB Clock. > - gEfiMdePkgTokenSpaceGuid.PcdFSBClock|200000000|UINT32|0x0000000c > - > ## The maximum printable number of characters. UefLib functions: AsciiPrint(), AsciiErrorPrint(), > # PrintXY(), AsciiPrintXY(), Print(), ErrorPrint() base on this PCD value to print characters. > # @Prompt Maximum Printable Number of Characters. > @@ -2297,5 +2293,9 @@ [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx] > # @Prompt Boot Timeout (s) > gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|0xffff|UINT16|0x0000002c > > + ## This value is used to configure X86 Processor FSB clock. > + # @Prompt FSB Clock. > + gEfiMdePkgTokenSpaceGuid.PcdFSBClock|200000000|UINT32|0x0000000c > + > [UserExtensions.TianoCore."ExtraFiles"] > MdePkgExtra.uni > Looks good to me: Reviewed-by: Laszlo Ersek <lersek@redhat.com> Mike or Liming will have to ACK. Thanks! Laszlo
Anthony: This change is OK to me. But if this PCD is configured as Dynamic, its value will be got from PCD service. This operation will take some time and cause the inaccurate time delay. Have you measured its impact? Thanks Liming > -----Original Message----- > From: Laszlo Ersek <lersek@redhat.com> > Sent: Thursday, January 30, 2020 12:11 AM > To: Anthony PERARD <anthony.perard@citrix.com>; devel@edk2.groups.io > Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>; xen-devel@lists.xenproject.org; > Gao, Liming <liming.gao@intel.com>; Justen, Jordan L <jordan.l.justen@intel.com>; Julien Grall <julien@xen.org>; Feng, Bob C > <bob.c.feng@intel.com> > Subject: Re: [PATCH 2/5] MdePkg: Allow PcdFSBClock to by Dynamic > > On 01/29/20 13:12, Anthony PERARD wrote: > > We are going to want to change the value of PcdFSBClock at run time in > > OvmfXen, so move it to the PcdsDynamic section. > > > > Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2490 > > Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> > > --- > > CC: Bob Feng <bob.c.feng@intel.com> > > CC: Liming Gao <liming.gao@intel.com> > > --- > > MdePkg/MdePkg.dec | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > diff --git a/MdePkg/MdePkg.dec b/MdePkg/MdePkg.dec > > index d022cc5e3ef2..8f5a48346e50 100644 > > --- a/MdePkg/MdePkg.dec > > +++ b/MdePkg/MdePkg.dec > > @@ -2194,10 +2194,6 @@ [PcdsFixedAtBuild,PcdsPatchableInModule] > > # @ValidList 0x80000001 | 8, 16, 32 > > gEfiMdePkgTokenSpaceGuid.PcdPort80DataWidth|8|UINT8|0x0000002d > > > > - ## This value is used to configure X86 Processor FSB clock. > > - # @Prompt FSB Clock. > > - gEfiMdePkgTokenSpaceGuid.PcdFSBClock|200000000|UINT32|0x0000000c > > - > > ## The maximum printable number of characters. UefLib functions: AsciiPrint(), AsciiErrorPrint(), > > # PrintXY(), AsciiPrintXY(), Print(), ErrorPrint() base on this PCD value to print characters. > > # @Prompt Maximum Printable Number of Characters. > > @@ -2297,5 +2293,9 @@ [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx] > > # @Prompt Boot Timeout (s) > > gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|0xffff|UINT16|0x0000002c > > > > + ## This value is used to configure X86 Processor FSB clock. > > + # @Prompt FSB Clock. > > + gEfiMdePkgTokenSpaceGuid.PcdFSBClock|200000000|UINT32|0x0000000c > > + > > [UserExtensions.TianoCore."ExtraFiles"] > > MdePkgExtra.uni > > > > Looks good to me: > > Reviewed-by: Laszlo Ersek <lersek@redhat.com> > > Mike or Liming will have to ACK. > > Thanks! > Laszlo
On Mon, Feb 03, 2020 at 01:34:55AM +0000, Gao, Liming wrote: > Anthony: > This change is OK to me. But if this PCD is configured as Dynamic, its value will be got from PCD service. This operation will take some time and cause the inaccurate time delay. Have you measured its impact? No, I haven't. But I don't think it matter in a Xen guest, the APIC timer is emulated anyway, so reading from a register of the APIC is going to be slower than getting the value from the PCD services, I think. (Hopefully, I'm not too wrong.) But I'll give it at measuring the difference, it would be interesting to know. Thanks,
On Mon, Feb 03, 2020 at 03:34:07PM +0000, Anthony PERARD wrote: > On Mon, Feb 03, 2020 at 01:34:55AM +0000, Gao, Liming wrote: > > Anthony: > > This change is OK to me. But if this PCD is configured as Dynamic, its value will be got from PCD service. This operation will take some time and cause the inaccurate time delay. Have you measured its impact? > > No, I haven't. But I don't think it matter in a Xen guest, the APIC timer is > emulated anyway, so reading from a register of the APIC is going to be > slower than getting the value from the PCD services, I think. > (Hopefully, I'm not too wrong.) > > But I'll give it at measuring the difference, it would be interesting to > know. Now that I've given a try, having the value as Dynamic doesn't change anything in a Xen guest. On my test machine, simply running GetPerformanceCounter (); takes between 10000 ns and 20000 ns. Reading the dynamic value from PCD on the other hand takes about 350ns. (10ns if it's static.) When I run NanoSecondDelay() with different values, I have: - with static pcd: 63894 ns to delay by 1 ns 66611 ns to delay by 10 ns 43927 ns to delay by 100 ns 71367 ns to delay by 1000 ns 55881 ns to delay by 10000 ns 147716 ns to delay by 100000 ns 1048335 ns to delay by 1000000 ns 10041179 ns to delay by 10000000 ns - with a dynamic pcd: 40949 ns to delay by 1 ns 84832 ns to delay by 10 ns 82745 ns to delay by 100 ns 59848 ns to delay by 1000 ns 52647 ns to delay by 10000 ns 137051 ns to delay by 100000 ns 1042492 ns to delay by 1000000 ns 10036306 ns to delay by 10000000 ns So, the kind of PCD used for PcdFSBClock on Xen (with OvmfXen) doesn't really matter. Anyway, thanks for the feedback.
Thanks for your data. Seemly, those data is acceptable on OvmfXen. For this patch, Reviewed-by: Liming Gao <liming.gao@intel.com> Thanks Liming > -----Original Message----- > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Anthony PERARD > Sent: Tuesday, February 4, 2020 1:26 AM > To: Gao, Liming <liming.gao@intel.com> > Cc: Laszlo Ersek <lersek@redhat.com>; devel@edk2.groups.io; Kinney, Michael D <michael.d.kinney@intel.com>; Ard Biesheuvel > <ard.biesheuvel@linaro.org>; xen-devel@lists.xenproject.org; Justen, Jordan L <jordan.l.justen@intel.com>; Julien Grall > <julien@xen.org>; Feng, Bob C <bob.c.feng@intel.com> > Subject: Re: [edk2-devel] [PATCH 2/5] MdePkg: Allow PcdFSBClock to by Dynamic > > On Mon, Feb 03, 2020 at 03:34:07PM +0000, Anthony PERARD wrote: > > On Mon, Feb 03, 2020 at 01:34:55AM +0000, Gao, Liming wrote: > > > Anthony: > > > This change is OK to me. But if this PCD is configured as Dynamic, its value will be got from PCD service. This operation will take > some time and cause the inaccurate time delay. Have you measured its impact? > > > > No, I haven't. But I don't think it matter in a Xen guest, the APIC timer is > > emulated anyway, so reading from a register of the APIC is going to be > > slower than getting the value from the PCD services, I think. > > (Hopefully, I'm not too wrong.) > > > > But I'll give it at measuring the difference, it would be interesting to > > know. > > Now that I've given a try, having the value as Dynamic doesn't change > anything in a Xen guest. > > On my test machine, simply running GetPerformanceCounter (); takes > between 10000 ns and 20000 ns. Reading the dynamic value from PCD on the > other hand takes about 350ns. (10ns if it's static.) > > When I run NanoSecondDelay() with different values, I have: > - with static pcd: > 63894 ns to delay by 1 ns > 66611 ns to delay by 10 ns > 43927 ns to delay by 100 ns > 71367 ns to delay by 1000 ns > 55881 ns to delay by 10000 ns > 147716 ns to delay by 100000 ns > 1048335 ns to delay by 1000000 ns > 10041179 ns to delay by 10000000 ns > - with a dynamic pcd: > 40949 ns to delay by 1 ns > 84832 ns to delay by 10 ns > 82745 ns to delay by 100 ns > 59848 ns to delay by 1000 ns > 52647 ns to delay by 10000 ns > 137051 ns to delay by 100000 ns > 1042492 ns to delay by 1000000 ns > 10036306 ns to delay by 10000000 ns > > So, the kind of PCD used for PcdFSBClock on Xen (with OvmfXen) doesn't > really matter. > > Anyway, thanks for the feedback. > > -- > Anthony PERARD > > -=-=-=-=-=-=-=-=-=-=-=- > Groups.io Links: You receive all messages sent to this group. > > View/Reply Online (#53675): https://edk2.groups.io/g/devel/message/53675 > Mute This Topic: https://groups.io/mt/70239981/1759384 > Group Owner: devel+owner@edk2.groups.io > Unsubscribe: https://edk2.groups.io/g/devel/unsub [liming.gao@intel.com] > -=-=-=-=-=-=-=-=-=-=-=-
diff --git a/MdePkg/MdePkg.dec b/MdePkg/MdePkg.dec index d022cc5e3ef2..8f5a48346e50 100644 --- a/MdePkg/MdePkg.dec +++ b/MdePkg/MdePkg.dec @@ -2194,10 +2194,6 @@ [PcdsFixedAtBuild,PcdsPatchableInModule] # @ValidList 0x80000001 | 8, 16, 32 gEfiMdePkgTokenSpaceGuid.PcdPort80DataWidth|8|UINT8|0x0000002d - ## This value is used to configure X86 Processor FSB clock. - # @Prompt FSB Clock. - gEfiMdePkgTokenSpaceGuid.PcdFSBClock|200000000|UINT32|0x0000000c - ## The maximum printable number of characters. UefLib functions: AsciiPrint(), AsciiErrorPrint(), # PrintXY(), AsciiPrintXY(), Print(), ErrorPrint() base on this PCD value to print characters. # @Prompt Maximum Printable Number of Characters. @@ -2297,5 +2293,9 @@ [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx] # @Prompt Boot Timeout (s) gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|0xffff|UINT16|0x0000002c + ## This value is used to configure X86 Processor FSB clock. + # @Prompt FSB Clock. + gEfiMdePkgTokenSpaceGuid.PcdFSBClock|200000000|UINT32|0x0000000c + [UserExtensions.TianoCore."ExtraFiles"] MdePkgExtra.uni
We are going to want to change the value of PcdFSBClock at run time in OvmfXen, so move it to the PcdsDynamic section. Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2490 Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> --- CC: Bob Feng <bob.c.feng@intel.com> CC: Liming Gao <liming.gao@intel.com> --- MdePkg/MdePkg.dec | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)