Date: Thu, 21 Jun 2012 09:47:30 -0400 From: John Baldwin <jhb@freebsd.org> To: Venkat Duvvuru <venkatduvvuru.ml@gmail.com> Cc: freebsd-net@freebsd.org Subject: Re: MSI-X limitation in freebsd 8.2 Message-ID: <201206210947.30171.jhb@freebsd.org> In-Reply-To: <CAGdae7Yum_MP99kSK1Xi8z02APnZPoXFKR22fTuE5tiuorYMhw@mail.gmail.com> References: <CAGdae7YW0jt4gTmHufHFTrcdtFGhngu_Wi%2BMDg1nY_T0J1C_SQ@mail.gmail.com> <201206210816.22774.jhb@freebsd.org> <CAGdae7Yum_MP99kSK1Xi8z02APnZPoXFKR22fTuE5tiuorYMhw@mail.gmail.com>
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On Thursday, June 21, 2012 8:50:06 am Venkat Duvvuru wrote: > While I'm able to ping to the machine..every command on the current active > session is sluggish infact doesn't complete, unable to open another ssh > session..an already opened ssh session doesn't react which is running > "systat -vmstat"... > > The only thing I could do is to successfully complete "top -P" command > once..even top hung for the second time. Hmm, is this a stock FreeBSD driver or an out-of-tree NIC driver? > /Venkat > > On Thu, Jun 21, 2012 at 5:46 PM, John Baldwin <jhb@freebsd.org> wrote: > > > On Thursday, June 21, 2012 5:47:48 am Venkat Duvvuru wrote: > > > John - Thanks for the reply. > > > > > > All the CPUs are ~100% idle. I don't see any interrupt storm on any of > > the > > > irqs (vmstat -i). > > > > > > One observation I made is that I see messages like these in dmesg > > > > > > ===> mem > > 0xfaf60000-0xfaf7ffff,0xfaf40000-0xfaf5ffff,0xfaf1c000-0xfaf1ffff > > > irq 40 at device 0.1 on pci6 > > > > > > Looking at the irq value I think it is the INTx irq range which shouldn't > > > have probably got allocated as the device is msix capable and there are > > > vectors allocated for these devices in the range (256-380). > > > > > > Could this be a problem? > > > > No, that line is output before the driver's attach routine is run, so it > > will > > always show INTx IRQ value even if it isn't used. > > > > > The scenario where I am hitting this problem is a setup with 4 NICs, each > > > NIC with two ports and each port using up 4 msix vectors. The system is > > > fine till some ports are up but once I ifup the 5th port, the system > > > becomes sluggish. > > > > > > I'm not sure whether all the 30 vectors are from a single cpu..I don't > > know > > > how to get that information. > > > > Unfortunately there isn't an easy way. I have this gdb script which can > > display it from kgdb on x86: > > > > define irqs > > set $e = event_list->tqh_first > > while ($e != 0) > > if ($e->ie_source != 0 && $e->ie_handlers.tqh_first != 0) > > set $src = (struct intsrc *)$e->ie_source > > if ($src->is_pic->pic_enable_source == &ioapic_enable_source) > > set $_cpu = ((struct ioapic_intsrc *)$src)->io_cpu > > else > > if ($src->is_pic->pic_enable_source == &msi_enable_source) > > set $_cpu = ((struct msi_intsrc *)$src)->msi_cpu > > else > > set $_cpu = 0 > > end > > end > > printf "CPU %d: %s\n", $_cpu, $e->ie_fullname > > end > > set $e = $e->ie_list.tqe_next > > end > > end > > > > document irqs > > Dump list of IRQs with associated CPU. > > end > > > > However, unless the driver is using BUS_BIND_IRQ() or you are using cpuset > > -x, > > the interrupts should be round-robin assigned among CPUs. > > > > What exactly do you mean by sluggish? Trying to interact with the box over > > SSH is sluggish? Is there a change in RTT if you are pinging the box, is > > there a change in performance of TCP or UDP streams to/from the box? > > > > -- > > John Baldwin > > > -- John Baldwin
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