On 25 March 2018 at 16:21, Paul Menzel <pmenzel+linux-efi@xxxxxxxxxxxxx> wrote: > Dear Ard, > > > On 03/25/2018 09:41 AM, Paul Menzel wrote: > >> On 03/24/2018 11:35 PM, Ard Biesheuvel wrote: >> >>> On 24 March 2018 at 22:10, Paul Menzel wrote: > > >>>> According to `initcall_debug`, `efisubsys_init` takes more than a few >>>> milliseconds to execute on a Dell XPS 13 9370 (Intel(R) Core(TM) >>>> i7-8550U CPU @ 1.80GHz). >>>> >>>>> ``` >>>>> […] >>>>> [ 0.144474] calling efisubsys_init+0x0/0x2cf @ 1 >>>>> [ 0.144474] Registered efivars operations >>>>> [ 0.173690] initcall efisubsys_init+0x0/0x2cf returned 0 after 27343 >>>>> usecs >>>>> […] >>>>> ``` >>>> >>>> >>>> >>>> To get a vanilla Linux kernel to boot in well under one second, it’d be >>>> nice >>>> if the time could be improved. Do you know, why it takes so long? >>>> >>>> According to `bootgraph.py` from pm-graph [1][2] it takes even a little >>>> longer. >>>> >>>>> efisubsys_init: start=690.841, end=720.493, length(w/o overhead)=31.250 >>>>> ms, return=0 >>>> >>>> >>>> There are several dozen calls to `virt_efi_get_next_variable()` all but >>>> one >>>> taking around 0.335 ms. This path needs to be optimized. Is that >>>> possible? >>> >>> >>> That depends. These are firmware calls, so to make these calls faster, >>> you need to modify the firmware, not the kernel. >> >> >> Yeah, unfortunately, no free firmware runs on this laptop, and Dell >> doesn’t respond to these kind of reports, as they think, it’s not important. >> >>> We may be able to make more intrusive changes to get rid of this >>> delay, e.g., spin up a special kernel thread, but I'd have to check in >>> more detail. >> >> >> That’d be great. >> >>> In the mean time, you can try passing 'efi=noruntime' to the kernel. >> >> >> Thank you, I didn’t know about that. Unfortunately, initcall_debug still >> reports the same time although the one message is gone. >> >> ``` >> $ sudo dmesg | grep efisubsys >> [ 0.145779] calling efisubsys_init+0x0/0x2cf @ 1 >> [ 0.172034] initcall efisubsys_init+0x0/0x2cf returned 0 after 27343 >> usecs >> ``` > > > Hmm, it looks like, I only edited `/etc/default/grub` and didn’t run `sudo > update-grub`. > > ``` > $ sudo dmesg | grep efisubsys > [ 0.776339] calling efisubsys_init+0x0/0x2cf @ 1 > [ 0.776339] initcall efisubsys_init+0x0/0x2cf returned 0 after 0 usecs > > ``` > Excellent! If you want it any faster than that, I can't really help you :-) -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
