Will Robert Love's new HZ patch make it into 1.4?

Freek · n00b Joined: 21 Oct 2002 Posts: 6 Location: Netherlands

Hi,

First, i'm new to the forums so please bare with me if i'm posting wrong somehow.

Robert Love has backported his HZ patch to the 2.4 kernel. As this is a performance patch _and_ Gentoo has a performance reputation to keep up, I wondered if this patch wil make it in Gentoo 1.4 or maybe it's allready in! I searched everywhere but I didn't find any references to it.

Cheers,

Fred van Zwieten (Freek)
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rac · Posted: Mon Oct 21, 2002 8:55 pm Post subject:

Is this patch substantially different from

Freek · n00b Joined: 21 Oct 2002 Posts: 6 Location: Netherlands

We'll, it sure looks like it's the same. The article on kerneltrap suggested it was a recent backport and I could not find any reference, so I thought i'd ask.

Well, if it's in, it's in, and that's good i guess

Cheers,

Fred van Zwieten (Freek)
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Make everything as simple as possible, but not simpler (Albert Einstein)

Lovechild · Posted: Mon Oct 21, 2002 9:06 pm Post subject:

what rml backported, wasn't really a timer fix for jiffies?

Because changing jiffy setting could, and would screw up the clock?

arkane · l33t Joined: 30 Apr 2002 Posts: 918 Location: Phoenix, AZ

The thing that bothers me the most about this patch is the limitation of ~49 days uptime.

Freek · n00b Joined: 21 Oct 2002 Posts: 6 Location: Netherlands

We'll, as I read it, the uptime reporting cycles every ~49 days, so if you don't bother about that, there's no problem.

I am confused however, according to rac the patch seemed to be allready included in gentoo-sources "for some time now". Doesn't that mean we should also have the ~49 days uptime issue?
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arkane · l33t Joined: 30 Apr 2002 Posts: 918 Location: Phoenix, AZ

rac · Posted: Mon Oct 21, 2002 9:38 pm Post subject:

Freek · n00b Joined: 21 Oct 2002 Posts: 6 Location: Netherlands

Well, maybe the 64bit-jiffies backport is also in. The discussion on the kerneltrap article is not clear on this being a actual problem. There are reports on succesfull and unsuccesfull jiffies wraparounds
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Mnemia · Guru Joined: 17 May 2002 Posts: 476

Well, I've got a server running gentoo-sources that will reach that limit in about a week and a half...if no one has figured this out by then I'll post back.

arkane · l33t Joined: 30 Apr 2002 Posts: 918 Location: Phoenix, AZ

Pigeon · Guru Joined: 21 Jun 2002 Posts: 307

Seems some gentoo users have encountered this in this thread. System didn't crash but it was fairly confusing. :lol:

Freek · n00b Joined: 21 Oct 2002 Posts: 6 Location: Netherlands

Okay, that sure seemes to confirm the jiffies patch is in. Anyone knows wether the 64bit jiffies will be in anytime soon, because that wil solve it kind of permanently.

From the other thread it looks like the box will survive a wraparound, but it's just, well, ugly. I can image some drivers will go crazy on it.
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Mnemia · Guru Joined: 17 May 2002 Posts: 476

Yes, I can confirm that it does roll over at 49 days. I concur with the other posters.

faz · Posted: Wed Nov 13, 2002 7:33 am Post subject:

Okay, perhaps there is a possibility to include the 64 bit jiffies backport in 1.4 so this confusion end's. It seems that not _all_ drivers are okay with a rollover, so it depend's on you're config whether this is a problem or not.

Any idea how to request the gentoo developers for inclusion?

Mnemia · Guru Joined: 17 May 2002 Posts: 476

File a bug in bugzilla and ask on the mailing lists; they're much more likely to read about it there than here in the forums.

When my server rolled over at 49 days, I didn't notice anything "not working", but then there could have been something subtle I didn't find in my cursory inspection (I've since rebooted it). As you've said, it's likely dependent on configuration. It should be fixed, though it's not a huge problem as long as people who are running servers that don't get rebooted often are aware of this limitation of those kernels. Perhaps a prominent mention in the install docs would be in order if a backport is not immediately feasible.

faz · Posted: Wed Nov 13, 2002 9:05 am Post subject:

Oke, i'll file a bug as soon as I can find the time. Thanx for the efforts

meekjt · n00b Joined: 22 Sep 2002 Posts: 27

Hello. What happens when the uptime rolls over? I'm using gentoo-sources 2.4.19-r9 with an uptime of 50 days, 11:16.

masseya · Posted: Fri Nov 15, 2002 12:14 am Post subject:

According to the thread that was linked to above, it seems as though it just resets your uptime.
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faz · Posted: Fri Nov 15, 2002 7:04 am Post subject:

There are also some reports about instabilities occuring and that's a Bad Thing. btw, i've requested inclusion of the 64bit jiffies in bugzilla.