[Bug 944347] Re: linux and initrd load very slowly on UEFI system

[Kamal Mostafa]

The performance problem appears to be due to overhead of the individual
disk read calls...

grub2's disk I/O layer buffers 8 disk sectors per read, hard-coded in
include/grub/disk.h as GRUB_DISK_CACHE_SIZE.

Increasing GRUB_DISK_CACHE_SIZE to 1024 (patch attached) dramatically
improves the load performance for my Intel Tunnel Mountain system
booting with UEFI:  total load time for linux and initrd is reduced from
about 53 seconds to about 1 second.

** Patch added: "kamal0~1024sectors.patch"
   https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/944347/+attachment/2798825/+files/kamal0%7E1024sectors.patch

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https://bugs.launchpad.net/bugs/944347

Title:
  linux and initrd load very slowly on UEFI system

Status in “grub2” package in Ubuntu:
  New

Bug description:
  On a Intel Tunnel Mountain system, grub2 loads from disk very slowly
  when booting with UEFI:  about 53 seconds to execute a pair of "linux"
  and "initrd" commands.

  Expected behavior:
      Load time for linux and initrd should be on order of 1 second.

  Problem observed with:
      grub2 (oneiric) 1.99-12ubuntu5
      grub2 (precise) 1.99-14ubuntu2
      Intel Tunnel Mountain UEFI BIOS version SDV.TM.B8 or SDV.TM.B9

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