Re: memory type information HOB / UEFI memmap defrag

["Kinney, Michael D" <michael.d.kinney@intel.com>]

Jordan,

The usage of EfiLoaderCode/ EfiBootServicesCode/ EfiBootServicesData
may vary from boot to boot, especially if the shell or other applications
are run or different OSes are booted.  A change in the bin size causes
extra variable writes and potentially extra reboots.

Mike

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Jordan Justen
> Sent: Tuesday, February 21, 2017 5:32 PM
> To: Yao, Jiewen <jiewen.yao@intel.com>; Laszlo Ersek <lersek@redhat.com>; edk2-devel-
> 01 <edk2-devel@lists.01.org>
> Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; Andrew Fish <afish@apple.com>; Ard Biesheuvel
> <ard.biesheuvel@linaro.org>
> Subject: Re: [edk2] memory type information HOB / UEFI memmap defrag
> 
> On 2017-02-21 16:46:40, Yao, Jiewen wrote:
> > HI Laszlo
> >
> > The purpose of this table to put OS consumed memory together to avoid S4 resume
> > issue. EfiLoaderCode/ EfiBootServicesCode/ EfiBootServicesData are not used by
> > OS. There is no need to put them here.
> >
> > I suggest we remove EfiLoaderCode/ EfiBootServicesCode/ EfiBootServicesData to
> > avoid confusing.
> >
> 
> Is there any other advantage to removing them?
> 
> I guess it would be easy enough to re-add them, but I don't think we
> need to move away from supporting S4. While I agree that S4 should not
> be a big priority, I'd prefer that we try to support it at some point.
> 
> -Jordan
> 
> >
> > > +  { EfiReservedMemoryType,  EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *   202) },
> > > +  { EfiLoaderCode,          EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *  1439) },
> > > +  { EfiBootServicesCode,    EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *  5980) },
> > > +  { EfiBootServicesData,    EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB * 41643) },
> > > +  { EfiRuntimeServicesCode, EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *  1025) },
> > > +  { EfiRuntimeServicesData, EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *  3629) },
> > > +  { EfiACPIReclaimMemory,   EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *    36) },
> > > +  { EfiACPIMemoryNVS,       EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *  1301) },
> > > +  { EfiMaxMemoryType,       0                                           }
> >
> >
> >
> > Thank you
> >
> > Yao Jiewen
> >
> >
> >
> > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Laszlo
> > Ersek
> > Sent: Tuesday, February 21, 2017 11:24 PM
> > To: edk2-devel-01 <edk2-devel@ml01.01.org>
> > Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; Justen, Jordan L
> > <jordan.l.justen@intel.com>; Andrew Fish <afish@apple.com>; Ard Biesheuvel
> > <ard.biesheuvel@linaro.org>
> > Subject: [edk2] memory type information HOB / UEFI memmap defrag
> >
> >
> >
> > Hi,
> >
> > the UEFI memmap under OVMF is getting very fragmented, I'm now counting
> > ~80 entries in it, under various circumstances.
> >
> > I recall that a platform's PlatformPei can "prime" the DXE/UEFI memory
> > allocation system (not the GCD services) for various memory types, by
> > producing a memory type information HOB.
> >
> > My vague understanding is that BDS will in turn check if the actual
> > allocations fit in the allotments from the HOB, and if not, it will try
> > to feed back the increased amount to PEI, for the next boot.
> >
> > As far as I understand, this requires the VariablePei (read only driver)
> > for a platform (so that its PlatformPei can read the info from BDS, and
> > produce the HOB accordingly). Some questions:
> >
> > - how big is VariablePei in binary form?
> > - does it depend on permanent RAM being installed / discovered?
> > - If so, is that dependency implemented with a static DEPEX, or with a
> >   callback?
> >
> > Further questions:
> > - what is the variable (GUID and Name) that BDS uses for this
> >   information?
> > - What is the format of the variable?
> > - Does the logic depend on particular boot modes? OVMF only supports two
> >   boot modes, BOOT_WITH_FULL_CONFIGURATION and BOOT_ON_S3_RESUME.
> >
> > In OVMF we currently use a static array for populating the HOB (see
> > "mDefaultMemoryTypeInformation" in "PlatformPei/Platform.c"). If making
> > it all dynamic is easy, I think I'd like to do it (sometime later).
> >
> > If, however, it would require us to up-end OVMF's PlatformPei, then I
> > think it's not worth it; we can just bump the values in
> > "mDefaultMemoryTypeInformation" suitably.
> >
> > Some examples I consider as up-ending OVMF's PlatformPei:
> >
> > (1) If VariablePei needs permanent RAM with a hard DEPEX. In OVMF,
> >     permanent RAM is installed by PlatformPei (thereby potentially
> >     unblocking VariablePei's dispatch); however, it is also PlatformPei
> >     that would require the r/o variable service to work, because
> >     PlatformPei produces the memory type information HOB. So, such a
> >     DEPEX in VariablePei would require splitting up PlatformPei, which
> >     makes the dynamism totally not worth it.
> >
> >     *Maybe* we could add a callback for when the variable service PPI is
> >     installed. Dunno.
> >
> > (2) Supporting a third boot mode beyond BOOT_WITH_FULL_CONFIGURATION and
> >     BOOT_ON_S3_RESUME. Not even worth the audit of current boot mode
> >     checks.
> >
> > Further remarks:
> >
> > - OVMF doesn't care about supporting S4 at the moment, and I personally
> >   have no plans to work on that. (I'm saying this because I vaguely
> >   recall that the memory type info HOB is related to S4 resume, so an
> >   argument could perhaps be made, "this could enable S4 for OVMF".
> >   Personally, I'm not interested. Still carrying the scars of S3.)
> >
> > - I actually tried to bump the values in "mDefaultMemoryTypeInformation"
> >   quite a few months back, but the benefits I saw were negligible. I was
> >   left confused about the memory type info HOB, and that was the reason
> >   I didn't ultimately post any patch (and why I stopped pursuing this
> >   question). For reference, this was the patch:
> >
> > > commit b357e8d88c0304ea2b31aefafe53d06c9769fb78
> > > Author: Laszlo Ersek <lersek@redhat.com>
> > > Date:   Thu Sep 17 16:18:46 2015 +0200
> > >
> > >     OvmfPkg: PlatformPei: decrease memmap fragmentation
> > >
> > >     Inspired by ArmVirtPkg commit c199315 ("ArmVirtPkg: increase memory
> > >     preallocations to reduce region count"), I checked the number of entries
> > >     in the UEFI memory map, as dumped by the UEFI shell's MEMMAP command, and
> > >     by the Linux kernel. The number of entries is quite high, about 50-55.
> > >
> > >     I calculated the new preallocations as follows:
> > >     - added 15% to each byte count usage reported by the MEMMAP command, for
> > >       some future-proofing,
> > >     - expressed the result in kilobytes (both pages and byte counts are hard
> > >       to read),
> > >     - just for our information, I calculated the ratio between the new
> > >       preallocation and the old one.
> > >
> > >     For example, the UEFI shell reported 44 pages (180224 bytes) of reserved
> > >     memory usage. The new preallocation, expressed in kilobytes, is
> > >     trunc(180224 * 1.15 / 1024) = 202. This preallocation is approx. 12.62
> > >     times the previous preallocation (which was 4 pages, ie. 16384 bytes).
> > >
> > >     Here's the full table:
> > >
> > >       memory type  pages from  bytes from  new KB    factor of former
> > >                    MEMMAP cmd  MEMMAP cmd  prealloc  prealloc
> > >       -----------  ----------  ----------  --------  ----------------
> > >       Reserved             44      180224       202             12.62
> > >       LoaderCode          313     1282048      1439               n/a
> > >       BS_Code            1300     5324800      5980              3.89
> > >       BS_Data            9053    37081088     41643              2.71
> > >       RT_Code             223      913408      1025              5.33
> > >       RT_Data             789     3231744      3629             25.20
> > >       ACPI_Recl             8       32768        36              1.12
> > >       ACPI_NVS            283     1159168      1301             81.31
> > >
> > >     ... Unfortunately, when the patch is applied, the memory map remains
> > >     fragmented;
> >  mostly due to small unused Conventional Memory entries between
> > >     other types of allocations. The entry count doesn't go below 40.
> > >
> > >     Contributed-under: TianoCore Contribution Agreement 1.0
> > >     Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> > >
> > > diff --git a/OvmfPkg/PlatformPei/Platform.c b/OvmfPkg/PlatformPei/Platform.c
> > > index a6d961673d3a..38abf3811600 100644
> > > --- a/OvmfPkg/PlatformPei/Platform.c
> > > +++ b/OvmfPkg/PlatformPei/Platform.c
> > > @@ -41,14 +41,15 @@
> > >  #include "Cmos.h"
> > >
> > >  EFI_MEMORY_TYPE_INFORMATION mDefaultMemoryTypeInformation[] = {
> > > -  { EfiACPIMemoryNVS,       0x004 },
> > > -  { EfiACPIReclaimMemory,   0x008 },
> > > -  { EfiReservedMemoryType,  0x004 },
> > > -  { EfiRuntimeServicesData, 0x024 },
> > > -  { EfiRuntimeServicesCode, 0x030 },
> > > -  { EfiBootServicesCode,    0x180 },
> > > -  { EfiBootServicesData,    0xF00 },
> > > -  { EfiMaxMemoryType,       0x000 }
> > > +  { EfiReservedMemoryType,  EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *   202) },
> > > +  { EfiLoaderCode,          EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *  1439) },
> > > +  { EfiBootServicesCode,    EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *  5980) },
> > > +  { EfiBootServicesData,    EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB * 41643) },
> > > +  { EfiRuntimeServicesCode, EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *  1025) },
> > > +  { EfiRuntimeServicesData, EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *  3629) },
> > > +  { EfiACPIReclaimMemory,   EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *    36) },
> > > +  { EfiACPIMemoryNVS,       EFI_SIZE_TO_PAGES ((UINTN)SIZE_1KB *  1301) },
> > > +  { EfiMaxMemoryType,       0                                           }
> > >  };
> > >
> > >
> >
> > As you can see in the commit message, at that time the patch only
> > managed to decrease the number of memmap entries from ~55 to ~40, which
> > I found "meh". I figured I'd ask again, because now I'm seeing about 80
> > entries in the memmap. (I wonder if that is related to OVMF's recently
> > increased ACPI S3 boot script usage!)
> >
> > Thanks,
> > Laszlo
> >
> > _______________________________________________
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> > edk2-devel@lists.01.org
> > https://lists.01.org/mailman/listinfo/edk2-devel
> >
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