Hi all, I have a customer server with 32 cores, 128G ram i7960X. So nice box... Why is it that "all" I am really doing at the moment is copying things to an external SSD disk USB3 connected and the machine "freezes"... Why is that? clearly plenty of CPU RAM everything... I can see "blocking" to write data to the external disk - but there are 31 other cores and plenty of memory to make it "seem" as nothing is happening right now. Do I need to 'tweak' something to no see GUI freezes... Waiting on characters to show - even remoted in with SSH experiences the same thing - so its not just X. Thanks for any suggestions. Jerry
On Mon, 5 Aug 2019 at 13:17, Jerry Geis <jerry.geis at gmail.com> wrote:> Hi all, > > I have a customer server with 32 cores, 128G ram i7960X. So nice box... > > Why is it that "all" I am really doing at the moment is copying things to > an external SSD disk USB3 connected and the machine "freezes"... Why is > that? > >You may have a motherboard which is routing a lot through a single USB controller. When that happens your graphical workstation will slow down because your keyboard and mouse events and some other polling has to complete before it can do the next thing. THis has nothing to do with the amount of RAM or cores in the system.. the hardware itself has been designed to have a blocking unit on it as can be seen by the fact that network logins are also freezing.> clearly plenty of CPU RAM everything... > I can see "blocking" to write data to the external disk - but there are 31 > other cores and plenty of memory to make it "seem" as nothing is happening > right now. > >Those 31 cores are waiting for the hardware backbus to be opened up for writing. Until that happens they are just spinning. Some of this depends on how the motherboard is designed and some of this may be x86 architecture issues.> Do I need to 'tweak' something to no see GUI freezes... Waiting on > characters to show - even remoted in with SSH experiences the same thing - > so its not just X. > > Thanks for any suggestions. > > Jerry > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos >-- Stephen J Smoogen.
Jerry Geis wrote:> > I have a customer server with 32 cores, 128G ram i7960X. So nice box... > > Why is it that "all" I am really doing at the moment is copying things to > an external SSD disk USB3 connected and the machine "freezes"... Why is > that? > > clearly plenty of CPU RAM everything... I can see "blocking" to write data > to the external disk - but there are 31 other cores and plenty of memory > to make it "seem" as nothing is happening right now. > > Do I need to 'tweak' something to no see GUI freezes... Waiting on > characters to show - even remoted in with SSH experiences the same thing - > so its not just X. > > Thanks for any suggestions. >What's top show? And maybe iostat? mark
On 8/5/19 10:17 AM, Jerry Geis wrote:> Do I need to 'tweak' something to no see GUI freezes... Waiting on > characters to show - even remoted in with SSH experiences the same thing - > so its not just X.Look at the output of "dmesg" and see if there are errors there.
There are no errors in dmesg. Top was showing 88% idle. If something is blocking somewhere as Stephen suggested - that's a major bummer. The keyboard is USB attached and the external SSD disk is USB attached. The mother board is an X299 UD4 Pro Anyway to use "nice" command to help with responiveness? I was just using "rsync . /media/external" to do the copy. Thanks, Jerry
On Mon, Aug 5, 2019 at 2:01 PM Jerry Geis <jerry.geis at gmail.com> wrote:> Anyway to use "nice" command to help with responiveness? I was just using > "rsync . /media/external" to do the copy. >You need to discover where it is blocking before deciding which solution will work. Something like iotop, atop, or other more wide system monitoring util will be more valuable than top/htop at this point since you seem to be sure that's it's not the processor usage that is the issue. nice will only work for scheduling processor use. There is the ionice command that can be used to set I/O priority. It really doesn't sound like you have a problem with process scheduling, so it's is probably more down the line of what you would want to try depending on what a system util tells you.
On Aug 5, 2019, at 11:25 AM, Stephen John Smoogen <smooge at gmail.com> wrote:> > On Mon, 5 Aug 2019 at 13:17, Jerry Geis <jerry.geis at gmail.com> wrote: > >> Why is it that "all" I am really doing at the moment is copying things to >> an external SSD disk USB3 connected and the machine "freezes"... Why is >> that? >> > You may have a motherboard which is routing a lot through a single USB > controller. When that happens your graphical workstation will slow down > because your keyboard and mouse events and some other polling has to > complete before it can do the next thing.Ridiculous if true. Modern OSes solved the blocking I/O problem decades ago. Consider: you may have a gigabit Ethernet connection to the Internet, and it is probably throttled to a small fraction of that speed by your ISP, yet you can be pumping hundreds of giga*bytes* per second to your SSD while your browser is blocked waiting for the remote server to respond. Further, while one site is being slow to respond, another background Internet task can use the idled Internet connection. This is a symptom of a real problem, and it may be well worth chasing it to the ground. Jerry: Try another I/O channel for the same copy. For example, what happens if you rsync the same file set to a remote machine, with the USB SSD connected to *that* machine? Or, if you have a Thunderbolt or FireWire option, try that instead. It might even be worth dropping a PCIe card into the machine for an alternative I/O path just to help diagnose this. If nothing else, it might solve the problem. USB is a terrible standard, emblematic of everything wrong with the PC world. We were sold USB-C as the grand unification of Thunderbolt and classic USB, but what we actually got are 6+ different and partially incompatible flavors of USB-C! https://people.kernel.org/bleung/how-many-kinds-of-usb-c-to-usb-c-cables-are-there https://news.ycombinator.com/item?id=20444326
On 8/5/19 3:00 PM, Jerry Geis wrote:> The keyboard is USB attached and the external SSD disk is USB attached.WHY? Why would you do that? What's the point of SSD if you reduce the speed to USB? Or just use an old mechanical drive instead. Any issue with that drive will show up as IO Wait - my presumption is that you expect to see that so you're not mentioning it but it's going to be extremely high. Remember, USB does not behave like SATA. And you may also find that the "max speed" in the specification is far from what you get out of your hardware. Use eSATA if you need it externally - not USB(3 or otherwise). -- Regards Peter Larsen