RFD: Should we remove the HLT check? (was Re: [PATCH 1/8] x86: avoid check hlt if no timer interrupts)
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From: H. Peter Anvin on 7 May 2010 16:40 On 05/07/2010 01:33 PM, Arjan van de Ven wrote: > On 5/7/2010 13:32, H. Peter Anvin wrote: >> >> I really wish I knew the exact systems affected by the HLT bug. If I >> remember correctly, it was some 386 systems -- or possibly 486 systems >> as well -- a very long time ago. This test just provides a diagnosis if >> the system really is bad (it hangs with an obvious message) at the cost >> of some 40 ms to the system boot time. I suspect C1 (HLT) being broken >> is not anywhere close to the predominant power management problem in the >> current day, and as such I'm wondering if this particular test hasn't >> outlived its usefulness. >> >> Thoughts? > > we could at least hide it behind the "don't run on pentium or newer" config options.. I'd be cool skipping it for family 5 or newer. I'm just wondering if we should kill it completely -- IIRC it was only a handful of 386/486 systems which had problems, usually due to marginal power supplies which couldn't handle the noise of a variable load (DOS not having any power management would run at a reliable 100% load) -- that's not exactly the type of systems which would have survived to modern day. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Arjan van de Ven on 7 May 2010 16:40 On 5/7/2010 13:32, H. Peter Anvin wrote: > > I really wish I knew the exact systems affected by the HLT bug. If I > remember correctly, it was some 386 systems -- or possibly 486 systems > as well -- a very long time ago. This test just provides a diagnosis if > the system really is bad (it hangs with an obvious message) at the cost > of some 40 ms to the system boot time. I suspect C1 (HLT) being broken > is not anywhere close to the predominant power management problem in the > current day, and as such I'm wondering if this particular test hasn't > outlived its usefulness. > > Thoughts? we could at least hide it behind the "don't run on pentium or newer" config options.. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Linus Torvalds on 7 May 2010 17:00 On Fri, 7 May 2010, Arjan van de Ven wrote: > On 5/7/2010 13:32, H. Peter Anvin wrote: > > > > I really wish I knew the exact systems affected by the HLT bug. If I > > remember correctly, it was some 386 systems -- or possibly 486 systems > > as well -- a very long time ago. This test just provides a diagnosis if > > the system really is bad (it hangs with an obvious message) at the cost > > of some 40 ms to the system boot time. I suspect C1 (HLT) being broken > > is not anywhere close to the predominant power management problem in the > > current day, and as such I'm wondering if this particular test hasn't > > outlived its usefulness. > > > > Thoughts? > > we could at least hide it behind the "don't run on pentium or newer" config > options.. Ack. That would take care of all relevant machines. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: H. Peter Anvin on 7 May 2010 17:10 On 05/07/2010 01:54 PM, Linus Torvalds wrote: > > > On Fri, 7 May 2010, Arjan van de Ven wrote: > >> On 5/7/2010 13:32, H. Peter Anvin wrote: >>> >>> I really wish I knew the exact systems affected by the HLT bug. If I >>> remember correctly, it was some 386 systems -- or possibly 486 systems >>> as well -- a very long time ago. This test just provides a diagnosis if >>> the system really is bad (it hangs with an obvious message) at the cost >>> of some 40 ms to the system boot time. I suspect C1 (HLT) being broken >>> is not anywhere close to the predominant power management problem in the >>> current day, and as such I'm wondering if this particular test hasn't >>> outlived its usefulness. >>> >>> Thoughts? >> >> we could at least hide it behind the "don't run on pentium or newer" config >> options.. > > Ack. That would take care of all relevant machines. > Sounds like a plan. Jacob, do you want to submit a new patch (bypassing this check if boot_cpu_info.x86 >= 5)? -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: jacob pan on 7 May 2010 18:10
>Sounds like a plan. Jacob, do you want to submit a new patch (bypassing >this check if boot_cpu_info.x86 >= 5)? > > -hpa > Just sent out the updated patch. I guess you meant boot_cpu_data instead of boot_cpu_info. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |