Messages in this thread Patch in this message | | | From | Boris Ostrovsky <> | Subject | [PATCH v2] x86/timers: Move simple_udelay_calibration() past kvmclock_init() | Date | Mon, 11 Sep 2017 14:51:11 -0400 |
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simple_udelay_calibration() relies on x86_platform's calibration ops. For KVM these ops are set late in setup_arch() and so simple_udelay_calibration() ends up using native version.
Besides being possibly incorrect, this significantly increases kernel boot time. For example, on my laptop executing start_kernel() by a guest takes ~10 times more than when KVM's ops are used.
Since early_xdbc_setup_hardware() relies on calibration having been performed move it too.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> --- v2: * Move xdbc initialization down as well.
Alternatively, we could start calling simple_udelay_calibration() only on bare metal: My understanding is that the only reason it exists is to help with USB3 earlyprink driver, which I don't think is useful to guests anyway.
arch/x86/kernel/setup.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index f81823695014..6e0e747d53bf 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1039,8 +1039,6 @@ void __init setup_arch(char **cmdline_p) */ init_hypervisor_platform(); - simple_udelay_calibration(); - x86_init.resources.probe_roms(); /* after parse_early_param, so could debug it */ @@ -1118,9 +1116,6 @@ void __init setup_arch(char **cmdline_p) memblock_set_current_limit(ISA_END_ADDRESS); e820__memblock_setup(); - if (!early_xdbc_setup_hardware()) - early_xdbc_register_console(); - reserve_bios_regions(); if (efi_enabled(EFI_MEMMAP)) { @@ -1221,6 +1216,10 @@ void __init setup_arch(char **cmdline_p) kvmclock_init(); #endif + simple_udelay_calibration(); + if (!early_xdbc_setup_hardware()) + early_xdbc_register_console(); + x86_init.paging.pagetable_init(); kasan_init(); -- 2.11.0
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