Em Tue, 28 Sep 2021 19:18:31 +0200 Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> escreveu: > On Tue, Sep 28, 2021 at 02:27:39PM +0200, Mauro Carvalho Chehab wrote: > > Em Tue, 28 Sep 2021 13:04:22 +0200 > > Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> escreveu: > > > > > On Tue, Sep 28, 2021 at 12:14:01PM +0200, Mauro Carvalho Chehab wrote: > > > > Hi Greg, > > > > > > > > As promised on > > > > > > > > https://lore.kernel.org/lkml/20210928120304.62319fba@xxxxxxxx/T/#u > > > > > > > > I'm adding progress info when get_abi.pl is checking for undefined ABI symbols > > > > on patches 1 and 2. > > > > > > > > That will help not only to identify what is causing delays on the script, but also > > > > to notify the user that processing it could take some time on some systems. > > > > > > > > If you run it on your big server with: > > > > > > > > scripts/get_abi.pl undefined 2>logs > > > > > > > > The "logs" file will contain timestamps relative to the time the script started to > > > > do the regex matches for sysfs files. It should be printing one line every > > > > time the progress completes 1% or one second after the last progress output. > > > > > > Adding more debugging and tweaking the script a bit to show the file it > > > is about to check, not the one it finished checking, > > > > Feel free to modify the script and add such debug/tweaks if you find > > it useful. > > > > > I got the following > > > debug output that seems to pinpoint the problem file. > > > > > > The sysfs file that is causing problems is: > > > /sys/devices/pci0000:40/0000:40:00.2/iommu/ivhd1/amd-iommu/cap > > > > > > and here's some debugging output for the regex it needs to search for > > > this: > > > > > > /sys/devices/pci0000:40/0000:40:00.2/iommu/ivhd1/amd-iommu/cap =~ /^(?^:^/sys/class/iommu/.*/amd\-iommu/cap$)$/ > > > /sys/devices/pci0000:40/0000:40:00.2/iommu/ivhd1/amd-iommu/cap =~ /^(?^:^/sys/class/iommu/.*/intel\-iommu/cap$)$/ > > > /sys/devices/pci0000:40/0000:40:00.2/iommu/ivhd1/amd-iommu/cap =~ /^(?^:^/sys/devices/pci.*.*.*.*\:.*.*/0000\:.*.*\:.*.*..*/dma/dma.*chan.*/quickdata/cap$)$/ > > > /sys/devices/pci0000:40/0000:40:07.0/iommu/amd-iommu/cap =~ /^(?^:^/sys/class/iommu/.*/amd\-iommu/cap$)$/ > > > /sys/devices/pci0000:40/0000:40:07.0/iommu/amd-iommu/cap =~ /^(?^:^/sys/class/iommu/.*/intel\-iommu/cap$)$/ > > > /sys/devices/pci0000:40/0000:40:07.0/iommu/amd-iommu/cap =~ /^(?^:^/sys/devices/pci.*.*.*.*\:.*.*/0000\:.*.*\:.*.*..*/dma/dma.*chan.*/quickdata/cap$)$/ > > > /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:02/device:7a/physical_node/iommu/ivhd1/amd-iommu/cap =~ /^(?^:^/sys/class/iommu/.*/amd\-iommu/cap$)$/ > > > /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:02/device:7a/physical_node/iommu/ivhd1/amd-iommu/cap =~ /^(?^:^/sys/class/iommu/.*/intel\-iommu/cap$)$/ > > > /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:02/device:7a/physical_node/iommu/ivhd1/amd-iommu/cap =~ /^(?^:^/sys/devices/pci.*.*.*.*\:.*.*/0000\:.*.*\:.*.*..*/dma/dma.*chan.*/quickdata/cap$)$/ > > > /sys/devices/pci0000:40/0000:40:01.3/0000:4a:00.0/0000:4b:0a.0/0000:50:00.0/iommu/amd-iommu/cap =~ /^(?^:^/sys/class/iommu/.*/amd\-iommu/cap$)$/ > > > /sys/devices/pci0000:40/0000:40:01.3/0000:4a:00.0/0000:4b:0a.0/0000:50:00.0/iommu/amd-iommu/cap =~ /^(?^:^/sys/class/iommu/.*/intel\-iommu/cap$)$/ > > > /sys/devices/pci0000:40/0000:40:01.3/0000:4a:00.0/0000:4b:0a.0/0000:50:00.0/iommu/amd-iommu/cap =~ /^(?^:^/sys/devices/pci.*.*.*.*\:.*.*/0000\:.*.*\:.*.*..*/dma/dma.*chan.*/quickdata/cap$)$/ > > > > Hmm... interesting. Perhaps the problem is on regexes like this: > > > > /^(?^:^/sys/devices/pci.*.*.*.*\:.*.*/0000\:.*.*\:.*.*..*/dma/dma.*chan.*/quickdata/cap$)$/ > > > > Which actually represents this What: > > /sys/devices/pciXXXX:XX/0000:XX:XX.X/dma/dma<n>chan<n>/quickdata/cap > > > > The script could have done a better job escaping "." character on > > it (but that is not too trivial) and grouping altogether ".*" > > repetitions, although, in this specific case, probably the best > > regex would be, instead: > > > > /sys/devices/pci[\da-f:\.]+/dma/dma\d+chan\d+/quickdata/cap > > > > One possible long-term solution would be to directly use regexes > > directly on "What" fields inside Documentation/ABI, but on some parts > > this would require some changes, like, for instance: > > > > /sys/bus/usb/devices/<busnum>-<devnum>:<config num>.<interface num>/<hid-bus>:<vendor-id>:<product-id>.<num>/kone/roccatkone<minor>/weight > > > > Ok, we could likely use capture groups like: > > > > (?<NAME>pattern) > > > > but IMO that would make it a lot harder to be understood by humans. > > > > > > > And sometimes this thing finishes in 20 seconds, and others, many many > > > minutes. It's not deterministic at all, which is odd. Is the sysfs > > > tree being sorted so that this should always have the same search order? > > > > No, because it uses a lot of hashes in order to speed it up. Yet, > > it shouldn't be hard - nor it would significantly affect the processing > > time - to make it more deterministic. See the enclosed path. > > That patch solved everything. > > It now only takes 10 seconds. Every time. Without the patch, it feels > hung for some reason. The explanation is simple - still weird :-) - basically, when an ABI symbol is found, the regex test loop stops. Sorting the regexes probably placed the slowest regex to happen *after* the one that matched the ABI symbol. > Care to turn that into a patch that I can take? Sure. Just sent it. > > > > Anyway, I've applied this series as well, this helps in finding the > > > problems :) > > > > Thanks! > > > > > Note, I can provide an off-list tarball of /sys/ if that would help in > > > debugging anything on your end. > > > > Yeah, that can help. Feel free to send it to me. > > > > Btw, I just got an arm64 server with 128 CPUs for testing. I'm trying > > to allocate also a big x86 server here, but I'm not sure if it is AMD or > > Intel. > > This is on perl 5.34 here. > > thanks, > > greg k-h Thanks, Mauro
