Re: [Xen-users] HVM boot time optimization

[George Dunlap <dunlapg@xxxxxxxxx>]

On Wed, Feb 7, 2018 at 1:11 PM, Yessine Daoud <da.yessine@xxxxxxxxx> wrote:

Hello,

Is there a way to make the boot of HVM guest faster?

I am using a direct kernel boot with kernel + ramdisk.

At boot, seabios is bloqued about 15 seconds (or more) at the following state:

(d4) RamSizeOver4G: 0x0000000000000000 [cmos]

(d4) boot order:

(d4) 1: /rom@genroms/linuxboot.bin

(d4) Found 4 PCI devices (max PCI bus is 00)

(d4) Allocated Xen hypercall page at ffff000

(d4) Detected Xen v4.9-unstable

(d4) xen: copy BIOS tables...

(d4) Copying SMBIOS entry point from 0x00010020 to 0x000f69b0

(d4) Copying MPTABLE from 0xfc001170/fc001180 to 0x000f68b0

(d4) Copying PIR from 0x00010040 to 0x000f6830

(d4) CPU Mhz=1335

(d4) Scan for VGA option rom

(d4) ATA controller 1 at 1f0/3f4/c100 (irq 14 dev 9)

(d4) ATA controller 2 at 170/374/c108 (irq 15 dev 9)

(d4) Found 0 lpt ports

(d4) Found 1 serial ports

(d4) PS2 keyboard initialized

(d4) All threads complete.

(d4) Scan for option roms

(d4) Running option rom at c000:0003

(d4) Searching bootorder for: /rom@genroms/linuxboot.bin

(d4) Searching bootorder for: HALT

(d4) Space available for UMB: c0800-ec800, f61d0-f67f0

(d4) Returned 258048 bytes of ZoneHigh

(d4) e820 map has 6 items:

(d4)   0: 0000000000000000 - 000000000009fc00 = 1 RAM

(d4)   1: 000000000009fc00 - 00000000000a0000 = 2 RESERVED

(d4)   2: 00000000000f0000 - 0000000000100000 = 2 RESERVED

(d4)   3: 0000000000100000 - 000000000ffff000 = 1 RAM

(d4)   4: 000000000ffff000 - 0000000010000000 = 2 RESERVED

(d4)   5: 00000000fc000000 - 0000000100000000 = 2 RESERVED

(d4) enter handle_19:

(d4)   NULL

(d4) Booting from ROM...

(d4) Booting from c000:00

Then (after 15 seconds) the kernel starts booting.

Is there a Xen configuration or Seabios patch that I can use?

Any idea?

Are you positive the kernel + ramdisk is actually working, and that it's not (for instance) actually running grub during this pause and pulling the default kernel off the disk?

On my box there's a brief pause there, about 5 seconds.  Total time from `xl create` to `responding to ssh` is about 15 seconds direct-boot HVM, 10 seconds direct-boot PVH or PV.  (This is with a CentOS 6 guest, which takes a bit longer to boot than newer systems in my experience.)

 -George

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