Date: Tue, 15 Oct 2024 21:43:47 +0900 From: Tomoaki AOKI <junchoon@dec.sakura.ne.jp> To: void <void@f-m.fm> Cc: freebsd-hackers@freebsd.org Subject: Re: polling interval Message-ID: <20241015214347.7717f2749fe5807c50d91031@dec.sakura.ne.jp> In-Reply-To: <Zw5CATFwkYWCCTB5@vm2> References: <Zw0Ez-zyTg9oodi8@int21h> <F86E4D26-E8A8-48D3-8407-E3AE35804CEE@lassitu.de> <Zw47GDCTyktxbUrx@vm2> <Zw5CATFwkYWCCTB5@vm2>
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On Tue, 15 Oct 2024 11:20:49 +0100 void <void@f-m.fm> wrote: > On Tue, Oct 15, 2024 at 10:51:20AM +0100, void wrote: > > >I'll next try setting kern.hz to -1 > > setting it to -1 returns a kern.hz value of 100 on reboot > setting it to 0 returns the kern.hz_min value of 8 > setting it to 1 and the kern.hz_min value to 1 still returns 8. -1 means "choose default". Behaviors for 0 and 1 would be because HZ_MINIMUM is defined as 8 in sys/sys/time.h, causing to clip to 8. > kern.hz=8 and kern.hz=100 gave the same numbers on bandwidth tests. > -- Maybe kern.hz=100 gives enough time (per tick) and kernel returns near the time even for kern.hz=8, disposing remaining time of the tick. # There was an abandoned review D40045 to reuse the disposed remaining # (fragmented) ticks. [1] And forgot tomention in my previous post. kern.hz for VMs (recognized as running on VM by FreeBSD kernel) is 100, as the default is HZ_VM. HZ and HZ_VM is defined as 1000 and 100 respectively, if not defined elsewhere. And if HZ_VM alone is not defined elsewhere, it is defined as HZ. These are because you see default kern.hz=100 on your VMs. [1] https://reviews.freebsd.org/D40045 -- Tomoaki AOKI <junchoon@dec.sakura.ne.jp>
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