Latency in logical volume layer?
I am trying to figure out a storage latency issue I am seeing with oVirt and iSCSI storage, and I am looking for a little help (or to be told "you're doing it wrong" as usual). I have an oVirt virtualization cluster running with 7 CentOS 7 servers, a dedicated storage LAN (separate switches), and iSCSI multipath running to a SAN. Occasionally, at times when there's no apparent load spike or anything, oVirt will report 5+ second latency accessing a storage domain. I can't see any network issue or problem at the SAN, so I started looking at Linux. oVirt reports this when it tries to read the storage domain metadata. With iSCSI storage, oVirt access it via multipath, and treats the whole device as a PV for Linux LVM (no partitioning). The metadata is a small LV that each node reads the first 4K from every few seconds (using O_DIRECT to avoid caching). I wrote a perl script to replicate this access pattern (open with O_DIRECT, read the first 4K, close) and report times. I do see higher than expected latency sometimes - 50-200ms latency happens fairly regularly. I added doing the same open/read/close on the PV (the multipath device), and I do not see the same latency there. It is a very consistent 0.25-0.55ms latency. I put a host in maintenance mode, and disabled multipath, and I saw similar behavior (comparing reads from the raw SCSI device and the LV device). I am testing on a host with no VMs. I do sometimes (not always) see similar latency on multiple hosts (others are running VMs) simultaneously. That's where I'm lost - how does going up the stack from the multipath device to the LV add so much latency (but not all the time)? I recognize that the CentOS 7 kernel is not mainline, but was hoping that maybe somebody would say "that's a known thing", or "that's expected", or "you're measuring wrong". Any suggestions, places to look, etc.? Thanks. -- Chris Adams
Disappearing RFC3041 IPv6 privacy addresses
Starting (I believe) with kernel 3.17, I am seeing RFC3041 IPv6 privacy addresses disappear while they are still in use. I have been seeing open SSH connections drop, and have finally seen one "dead" but not yet closed. At that point "ss -t" shows an ESTAB socket with a local address that is no longer listed by "ip -6 addr list br1". This is on a Fedora 20 system, currently running the Fedora 3.17.7-200.fc20.x86_64 kernel. I don't know if it matters, but my network setup is a router running OpenWRT and just IPv6 RAs and SLAAC (DHCPv6 disabled). -- Chris Adams -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: New system call wanted: fdreopen
Once upon a time, Tristan Wibberley said: >A common idiom on Linux is to open a file and keep the fd open so that >the underlying file can be unlinked from its directory. But if the file >needs to be read from several different parts of the codebase then due to >the file descriptor having exactly one read pointer those different parts >must be synchronised which is a relatively difficult task. I think you can get similar behavior entirely in user space and in a fashion portable to at least BSD systems. You could fork() (which would create a separate FD in the child), pass the FD back to the parent over a socket, and then have the child exit. -- Chris Adams Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 00/36] AArch64 Linux kernel port
Once upon a time, Catalin Marinas said: >Changing the arch/ dir name is easy at this point. My preference is for >consistency with the official name (that cannot be changed) and the gcc >triplet. What ARM Ltd. says is the "official" name isn't necessarily what the rest of the world will call it. Linux uses "i386" for what Intel calls "IA-32" (which virtually nobody else uses). -- Chris Adams Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: sys_chroot+sys_fchdir Fix
Once upon a time, Alan Cox <[EMAIL PROTECTED]> said: >Well if citing standards documents at people is rudeness so be it. I hate to get involved in this, but actually chroot() is no longer part of SuS as of version 3. For other Unix versions, both Tru64 (5.1B) and Solaris (9) chroot(2) man pages also say the working directory is unaffected by chroot(). The Solaris man page explicitly mentions using fchdir() to reset the root to a previously opened directory however. On Tru64 and Solaris, the chroot command does call chdir() after chroot(), but that is a userspace thing. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Dual-Licensing Linux Kernel with GPL V2 and GPL V3
Once upon a time, <[EMAIL PROTECTED]> said: >do you realize that redhat uses checksums or signatures to check the >validity of their CD's? > >try to burn a redhat image with the -pad option which adds a chunk of 0's >to the end of the image and try to boot it. It'll boot and run just fine. The checksum is simply an optional integrity check (you can bypass it by choosing "Skip" when it prompts to test your CD/DVD). >I seriously doubt if redhat tells you how to how to generate such a >checksum/signature. You are seriously wrong then. The tool is in the anaconda package, and there are docs on using it both there and many places on the web. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Dual-Licensing Linux Kernel with GPL V2 and GPL V3
Once upon a time, Bron Gondwana <[EMAIL PROTECTED]> said: > To be fair here, this could also be accomplished by having to flip a > physical switch on the router, especially if you did something funky > like: > > [---] push this button for a 5 minute access pass to upload new > software through physical cable port 1. > > More complex, but not unreasonable. Well, there is no restriction on putting files on the routing engine's storage devices (flash and hard drive); it is running OpenSSH, so scp/sftp work fine, and you can drop to a shell easily. The restriction is that the kernel won't run unsigned binaries. Also, flipping physical switches is pretty much an unreasonable expectation for core router operation. These are often in other locations, sometimes other telcos' central offices (where you have to pay to have "remote hands" do something and then hope they don't screw it up). You can easily go the entire life of a device where the primary operators never physically see the device. -- Chris Adams <[EMAIL PROTECTED]> Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Dual-Licensing Linux Kernel with GPL V2 and GPL V3
Once upon a time, Jesper Juhl <[EMAIL PROTECTED]> said: >Let's say I'm the owner of a company selling some device that uses a >GPLv2 OS and some GPLv2 applications to do the job. Let's say that for >some reason I don't want the end users of my device to tinker with the >software inside my device. Obviously I release the source for any >modifications I may have made, but I use the hardware to prevent users >from installing modified versions on the device (basically I TiVO'ize >the device). BTW: Another reason a vendor might lock down the device is for security. For example, Juniper routers (which now run a significant portion of the "core" of the Internet) run FreeBSD on the routing engine. They include several GNU software utilities (for example gawk, diff, and gdb). Starting with JUNOS 7.6 (IIRC), end-users can no longer build and run their own binaries on the routing engine. This means that the GPLv2 code cannot be modified in-place (similar to TiVo altough done using different means). The reason is that if there ever is a security hole in the routing engine software (FreeBSD kernel, OpenSSH, etc.), it would be a really bad thing if crackers could load arbitrary software (rootkits, spam software, etc.) directly on Internet core routers. If you think spam zombies on cable modems or DSL are bad, imagine them on 100 megabit links! - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Dual-Licensing Linux Kernel with GPL V2 and GPL V3
Once upon a time, Alexandre Oliva <[EMAIL PROTECTED]> said: >But at least my participation in this thread was to show that GPLv3 >does not indeed change the spirit, unlike others who missed or >misunderstood the spirit claimed. What you continue to miss is that "the spirit of the GPL" is some mystical thing that is not well-defined. You have one iterpretation, and this thread has shown that others have other interpretation. >It is not fair to claim that GPLv3 changes the spirit of the GPL. For some people it is fair, because they have interpreted the GPLv2 differently than others for 15 years now. Obviously Linus feels that the spirit of the GPLv2 is exactly what he wanted and that it allows TiVo to lock down their hardware. You obviously disagree. Stop telling everyone else they are wrong and you are right when they disagree with your intepretation. The GPLv2 never defines "the spirit of the GPL" so others are free to get different meanings from it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Dual-Licensing Linux Kernel with GPL V2 and GPL V3
Once upon a time, Alexandre Oliva <[EMAIL PROTECTED]> said: >> What the GPL *does* say is that you can't "add additional >> restrictions to the license" > >Not quite. It's more general than that: > > You may not impose any further restrictions on the recipients' > exercise of the rights granted herein. GPLv2 section 0 says: Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, ... The license does not cover running of the program. It doesn't restrict it, but it doesn't cover it. Claiming otherwise is turning the GPL into yet another dreaded EULA. Nowhere does the GPLv2 define modification as "modify and run in place". The Preamble emphasizes sharing; hardware is a fixed object and can't be shared in the same fashion as software. Also, GPLv2 section 2 includes: In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License. TiVo's firmware (and any restrictions it may carry) is not affected by the GPLv2. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Dual-Licensing Linux Kernel with GPL V2 and GPL V3
Once upon a time, Alexandre Oliva <[EMAIL PROTECTED]> said: > if you distribute copies of such a program, [...] > you must give the recipients all the rights that you have > >So, TiVo includes a copy of Linux in its DVR. > >TiVo retains the right to modify that copy of Linux as it sees fit. > >It doesn't give the recipients the same right. Sure it does; you received a program (the kernel) and you can modify it. You also received hardware; they don't support modification of that. Nowhere in the license does it say they have to, because the license only covers the program. Or are you claiming that putting software on hardware makes the result a derivative work? I think it falls under the "mere aggregation" clause. What if TiVo had put the kernel in a burned-in ROM (not flash, or on a flash ROM with no provision for reprogramming it)? Would that also violate the "spirit" of the GPL? Must any device that wishes to include GPL code include additional hardware to support replacing that code (even if that hardware is otherwise superfluous)? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: ExpressCard hotswap support?
Once upon a time, Daniel J Blueman <[EMAIL PROTECTED]> said: > On 4 May, 01:20, Chris Adams <[EMAIL PROTECTED]> wrote: > >I've got a Thinkpad Z60m with an ExpressCard slot, and I got a Belkin > >F5U250 GigE ExpressCard (Marvell 88E8053 chip using sky2 driver). It > >appears that Linux only recognizes it if I insert the card with the > >system powered off. If I hot-insert the card, nothing happens (no > >messages logged, no PCI device shows up, nothing). > > The BIOS initialises and powers up the downstream PCI express port > when it detects a card is present. > > When Linux boots, it enumerates the bus and sees it, but does not do > prior configuration to enable, configure and cause link negotiation on > all PCI express ports I believe; this requires chipset and (sometimes > revision-) specific code, which wouldn't be so robust as the BIOS > doing the footwork. Actually, for me, loading pciehp with pciehp_force=1 set works. -- Chris Adams <[EMAIL PROTECTED]> Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
ExpressCard hotswap support?
I've got a Thinkpad Z60m with an ExpressCard slot, and I got a Belkin F5U250 GigE ExpressCard (Marvell 88E8053 chip using sky2 driver). It appears that Linux only recognizes it if I insert the card with the system powered off. If I hot-insert the card, nothing happens (no messages logged, no PCI device shows up, nothing). Does Linux support hotswapping ExpressCards? This is with Fedora Core 6 with all updates, kernel 2.6.20-1.2948.fc6. -- Chris Adams <[EMAIL PROTECTED]> Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Why ask Sun for ZFS while we have ReiserFS4 !?
Once upon a time, Theodore Tso <[EMAIL PROTECTED]> said: >The people who want ZFS have in mind certain features, such as the >ability to scale to very large sizes, and ease of use when >administering filesystems that span multiple disks (ZFS subsumes the >device-mapper/RAID layer in Solaris, so they get certain performance >benefits and they are able to make it simpler to set up a filesystem >that spans multiple disks with a single command --- the flip side is >that they are violating an relatively well understood abstraction >boundary, for better or for worse). I haven't used ZFS, but I do manage servers with Tru64 Unix AdvFS filesystems. Having some of the logical volume functionality merged in the filesystem layer does seem to be a good thing. For example, snapshotting a filesystem can use free space in the filesystem (without having to set aside unused logical volume space for snapshotting). Expanding the filesystem is simple: "addvol " and go (no adding to the volume group, extending the logical volume, and resizing the filesystem). Shrinking the filesystem is just as easy (currently you can't even do that live with ext3). I know this violates the Linux layering. However, AdvFS has done this for years (in a single-system-image cluster environment even), and now I guess ZFS does it as well. Maybe the Linux layering needs a revision to handle something like this? I'm just speaking as a system admin that prefers Linux everywhere, but does like (and will miss) a few things about Tru64/TruCluster. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] Stop pmac_zilog from abusing 8250's device numbers.
Once upon a time, Brad Boyer <[EMAIL PROTECTED]> said: >The point is that people are used to having "ttyS0" mean the first >onboard serial port. My first serial port is a USB dongle and is ttyUSB0. If the argument is that all serials should be ttyS[0-9]+, are you going to change USB adapters as well? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: util-linux: orphan
Once upon a time, Arnd Bergmann <[EMAIL PROTECTED]> said: >I saw that the current Fedora already dynamically links /bin/mount >against /usr/lib/libblkid.so. What do you mean by "current" Fedora? I think the first Fedora version that linked /bin/mount against libblkid.so was FC4, and FC4, FC5, FC6, and rawhide all have libblkid.so in /lib. -- Chris Adams <[EMAIL PROTECTED]> Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: File corruption on LVM2 on top of software RAID1
Once upon a time, "Simon Matter" <[EMAIL PROTECTED]> said: >In my tests I get corrupt files on LVM2 which is on top of software raid1. >(This is a common setup even mentioned in the software RAID HOWTO and has >worked for me on RedHat 9 / kernel 2.4 for a long time now and it's my >favourite configuration). Now, I tested two different distributions, three >kernels, three different filesystems and three different hardware. I can >always reproduce it with the following easy scripts: See: http://bugzilla.kernel.org/show_bug.cgi?id=4946 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=152162 There's a one-line patch in there; see if that fixes the problem for you. -- Chris Adams <[EMAIL PROTECTED]> Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: temperature standard - global config option?
Once upon a time, L. K. <[EMAIL PROTECTED]> said: >On Thu, 7 Jun 2001, Albert D. Cahalan wrote: >> Negative temperatures do not really exist. > >Are you really sure about this ? He's positive! -- Chris Adams <[EMAIL PROTECTED]> Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH/REQ] Increase kmsg buffer from 16K to 32K, kernel/printk.c
Once upon a time, David Ford <[EMAIL PROTECTED]> said: >The largest bodies of text come from scsi, irda, usb, and udf. Don't forget software RAID. You get gobs of output from autodetect and startup of each filesystem (so if you have 6 or so RAID filesystems, you can get over 13kB of messages). -- Chris Adams <[EMAIL PROTECTED]> Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
"hdx=bswap" doesn't work in 2.4.0-test9
I'm trying to read an IDE drive from a different architecture on my x86 PC, and "hda=bswap" doesn't seem to work anymore. The option is recognized (because I get "ide_setup: hda=bswap" in the boot output) but it does not appear to have any effect. -- Chris Adams <[EMAIL PROTECTED]> Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
