1. 03 Jun, 2021 4 commits
    • Martin Belanger's avatar
      nvme-tcp: allow selecting the network interface for connections · 3ede8f72
      Martin Belanger authored
      In our application, we need a way to force TCP connections to go out a
      specific IP interface instead of letting Linux select the interface
      based on the routing tables.
      
      Add the 'host-iface' option to allow specifying the interface to use.
      When the option host-iface is specified, the driver uses the specified
      interface to set the option SO_BINDTODEVICE on the TCP socket before
      connecting.
      
      This new option is needed in addtion to the existing host-traddr for
      the following reasons:
      
      Specifying an IP interface by its associated IP address is less
      intuitive than specifying the actual interface name and, in some cases,
      simply doesn't work. That's because the association between interfaces
      and IP addresses is not predictable. IP addresses can be changed or can
      change by themselves over time (e.g. DHCP). Interface names are
      predictable [1] and will persist over time. Consider the following
      configuration.
      
      1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state ...
          link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
          inet 100.0.0.100/24 scope global lo
             valid_lft forever preferred_lft forever
      2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc ...
          link/ether 08:00:27:21:65:ec brd ff:ff:ff:ff:ff:ff
          inet 100.0.0.100/24 scope global enp0s3
             valid_lft forever preferred_lft forever
      3: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc ...
          link/ether 08:00:27:4f:95:5c brd ff:ff:ff:ff:ff:ff
          inet 100.0.0.100/24 scope global enp0s8
             valid_lft forever preferred_lft forever
      
      The above is a VM that I configured with the same IP address
      (100.0.0.100) on all interfaces. Doing a reverse lookup to identify the
      unique interface associated with 100.0.0.100 does not work here. And
      this is why the option host_iface is required. I understand that the
      above config does not represent a standard host system, but I'm using
      this to prove a point: "We can never know how users will configure
      their systems". By te way, The above configuration is perfectly fine
      by Linux.
      
      The current TCP implementation for host_traddr performs a
      bind()-before-connect(). This is a common construct to set the source
      IP address on a TCP socket before connecting. This has no effect on how
      Linux selects the interface for the connection. That's because Linux
      uses the Weak End System model as described in RFC1122 [2]. On the other
      hand, setting the Source IP Address has benefits and should be supported
      by linux-nvme. In fact, setting the Source IP Address is a mandatory
      FedGov requirement (e.g. connection to a RADIUS/TACACS+ server).
      Consider the following configuration.
      
      $ ip addr list dev enp0s8
      3: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc ...
          link/ether 08:00:27:4f:95:5c brd ff:ff:ff:ff:ff:ff
          inet 192.168.56.101/24 brd 192.168.56.255 scope global enp0s8
             valid_lft 426sec preferred_lft 426sec
          inet 192.168.56.102/24 scope global secondary enp0s8
             valid_lft forever preferred_lft forever
          inet 192.168.56.103/24 scope global secondary enp0s8
             valid_lft forever preferred_lft forever
          inet 192.168.56.104/24 scope global secondary enp0s8
             valid_lft forever preferred_lft forever
      
      Here we can see that several addresses are associated with interface
      enp0s8. By default, Linux always selects the default IP address,
      192.168.56.101, as the source address when connecting over interface
      enp0s8. Some users, however, want the ability to specify a different
      source address (e.g., 192.168.56.102, 192.168.56.103, ...). The option
      host_traddr can be used as-is to perform this function.
      
      In conclusion, I believe that we need 2 options for TCP connections.
      One that can be used to specify an interface (host-iface). And one that
      can be used to set the source address (host-traddr). Users should be
      allowed to use one or the other, or both, or none. Of course, the
      documentation for host_traddr will need some clarification. It should
      state that when used for TCP connection, this option only sets the
      source address. And the documentation for host_iface should say that
      this option is only available for TCP connections.
      
      References:
      [1] https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
      [2] https://tools.ietf.org/html/rfc1122
      
      Tested both IPv4 and IPv6 connections.
      Signed-off-by: default avatarMartin Belanger <martin.belanger@dell.com>
      Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
      Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      3ede8f72
    • Mario Limonciello's avatar
      nvme-pci: look for StorageD3Enable on companion ACPI device instead · e21e0243
      Mario Limonciello authored
      The documentation around the StorageD3Enable property hints that it
      should be made on the PCI device.  This is where newer AMD systems set
      the property and it's required for S0i3 support.
      
      So rather than look for nodes of the root port only present on Intel
      systems, switch to the companion ACPI device for all systems.
      David Box from Intel indicated this should work on Intel as well.
      
      Link: https://lore.kernel.org/linux-nvme/YK6gmAWqaRmvpJXb@google.com/T/#m900552229fa455867ee29c33b854845fce80ba70
      Link: https://docs.microsoft.com/en-us/windows-hardware/design/component-guidelines/power-management-for-storage-hardware-devices-intro
      Fixes: df4f9bc4 ("nvme-pci: add support for ACPI StorageD3Enable property")
      Suggested-by: default avatarLiang Prike <Prike.Liang@amd.com>
      Acked-by: default avatarRaul E Rangel <rrangel@chromium.org>
      Signed-off-by: default avatarMario Limonciello <mario.limonciello@amd.com>
      Reviewed-by: default avatarDavid E. Box <david.e.box@linux.intel.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      e21e0243
    • Alexey Bogoslavsky's avatar
      nvme: extend and modify the APST configuration algorithm · ebd8a93a
      Alexey Bogoslavsky authored
      The algorithm that was used until now for building the APST configuration
      table has been found to produce entries with excessively long ITPT
      (idle time prior to transition) for devices declaring relatively long
      entry and exit latencies for non-operational power states. This leads
      to unnecessary waste of power and, as a result, failure to pass
      mandatory power consumption tests on Chromebook platforms.
      
      The new algorithm is based on two predefined ITPT values and two
      predefined latency tolerances. Based on these values, as well as on
      exit and entry latencies reported by the device, the algorithm looks
      for up to 2 suitable non-operational power states to use as primary
      and secondary APST transition targets. The predefined values are
      supplied to the nvme driver as module parameters:
      
       - apst_primary_timeout_ms (default: 100)
       - apst_secondary_timeout_ms (default: 2000)
       - apst_primary_latency_tol_us (default: 15000)
       - apst_secondary_latency_tol_us (default: 100000)
      
      The algorithm echoes the approach used by Intel's and Microsoft's drivers
      on Windows. The specific default parameter values are also based on those
      drivers. Yet, this patch doesn't introduce the ability to dynamically
      regenerate the APST table in the event of switching the power source from
      AC to battery and back. Adding this functionality may be considered in the
      future. In the meantime, the timeouts and tolerances reflect a compromise
      between values used by Microsoft for AC and battery scenarios.
      
      In most NVMe devices the new algorithm causes them to implement a more
      aggressive power saving policy. While beneficial in most cases, this
      sometimes comes at the price of a higher IO processing latency in certain
      scenarios as well as at the price of a potential impact on the drive's
      endurance (due to more frequent context saving when entering deep non-
      operational states). So in order to provide a fallback for systems where
      these regressions cannot be tolerated, the patch allows to revert to
      the legacy behavior by setting either apst_primary_timeout_ms or
      apst_primary_latency_tol_us parameter to 0. Eventually (and possibly after
      fine tuning the default values of the module parameters) the legacy behavior
      can be removed.
      
      TESTING.
      
      The new algorithm has been extensively tested. Initially, simulations were
      used to compare APST tables generated by old and new algorithms for a wide
      range of devices. After that, power consumption, performance and latencies
      were measured under different workloads on devices from multiple vendors
      (WD, Intel, Samsung, Hynix, Kioxia). Below is the description of the tests
      and the findings.
      
      General observations.
      The effect the patch has on the APST table varies depending on the entry and
      exit latencies advertised by the devices. For some devices, the effect is
      negligible (e.g. Kioxia KBG40ZNS), for some significant, making the
      transitions to PS3 and PS4 much quicker (e.g. WD SN530, Intel 760P), or making
      the sleep deeper, PS4 rather than PS3 after a similar amount of time (e.g.
      SK Hynix BC511). For some devices (e.g. Samsung PM991) the effect is mixed:
      the initial transition happens after a longer idle time, but takes the device
      to a lower power state.
      
      Workflows.
      In order to evaluate the patch's effect on the power consumption and latency,
      7 workflows were used for each device. The workflows were designed to test
      the scenarios where significant differences between the old and new behaviors
      are most likely. Each workflow was tested twice: with the new and with the
      old APST table generation implementation. Power consumption, performance and
      latency were measured in the process. The following workflows were used:
      1) Consecutive write at the maximum rate with IO depth of 2, with no pauses
      2) Repeated pattern of 1000 consecutive writes of 4K packets followed by 50ms
         idle time
      3) Repeated pattern of 1000 consecutive writes of 4K packets followed by 150ms
         idle time
      4) Repeated pattern of 1000 consecutive writes of 4K packets followed by 500ms
         idle time
      5) Repeated pattern of 1000 consecutive writes of 4K packets followed by 1.5s
         idle time
      6) Repeated pattern of 1000 consecutive writes of 4K packets followed by 5s
         idle time
      7) Repeated pattern of a single random read of a 4K packet followed by 150ms
         idle time
      
      Power consumption
      Actual power consumption measurements produced predictable results in
      accordance with the APST mechanism's theory of operation.
      Devices with long entry and exit latencies such as WD SN530 showed huge
      improvement on scenarios 4,5 and 6 of up to 62%. Devices such as Kioxia
      KBG40ZNS where the resulting APST table looks virtually identical with
      both legacy and new algorithms, showed little or no change in the average power
      consumption on all workflows. Devices with extra short latencies such as
      Samsung PM991 showed moderate increase in power consumption of up to 18% in
      worst case scenarios.
      In addition, on Intel and Samsung devices a more complex impact was observed
      on scenarios 3, 4 and 7. Our understanding is that due to longer stay in deep
      non-operational states between the writes the devices start performing background
      operations leading to an increase of power consumption. With the old APST tables
      part of these operations are delayed until the scenario is over and a longer idle
      period begins, but eventually this extra power is consumed anyway.
      
      Performance.
      In terms of performance measured on sustained write or read scenarios, the
      effect of the patch is minimal as in this case the device doesn't enter low power
      states.
      
      Latency
      As expected, in devices where the patch causes a more aggressive power saving
      policy (e.g. WD SN530, Intel 760P), an increase in latency was observed in
      certain scenarios. Workflow number 7, specifically designed to simulate the
      worst case scenario as far as latency is concerned, indeed shows a sharp
      increase in average latency (~2ms -> ~53ms on Intel 760P and 0.6 -> 10ms on
      WD SN530). The latency increase on other workloads and other devices is much
      milder or non-existent.
      Signed-off-by: default avatarAlexey Bogoslavsky <alexey.bogoslavsky@wdc.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      ebd8a93a
    • Colin Ian King's avatar
      nvme: remove redundant initialization of variable ret · 13ce7e62
      Colin Ian King authored
      The variable ret is being initialized with a value that is never read,
      it is being updated later on. The assignment is redundant and can be
      removed.
      Signed-off-by: default avatarColin Ian King <colin.king@canonical.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      13ce7e62
  2. 24 May, 2021 13 commits
  3. 23 May, 2021 18 commits
  4. 22 May, 2021 4 commits
    • Linus Torvalds's avatar
      Merge tag 'block-5.13-2021-05-22' of git://git.kernel.dk/linux-block · 4ff2473b
      Linus Torvalds authored
      Pull block fixes from Jens Axboe:
      
       - Fix BLKRRPART and deletion race (Gulam, Christoph)
      
       - NVMe pull request (Christoph):
            - nvme-tcp corruption and timeout fixes (Sagi Grimberg, Keith
              Busch)
            - nvme-fc teardown fix (James Smart)
            - nvmet/nvme-loop memory leak fixes (Wu Bo)"
      
      * tag 'block-5.13-2021-05-22' of git://git.kernel.dk/linux-block:
        block: fix a race between del_gendisk and BLKRRPART
        block: prevent block device lookups at the beginning of del_gendisk
        nvme-fc: clear q_live at beginning of association teardown
        nvme-tcp: rerun io_work if req_list is not empty
        nvme-tcp: fix possible use-after-completion
        nvme-loop: fix memory leak in nvme_loop_create_ctrl()
        nvmet: fix memory leak in nvmet_alloc_ctrl()
      4ff2473b
    • Linus Torvalds's avatar
      Merge tag 'io_uring-5.13-2021-05-22' of git://git.kernel.dk/linux-block · b9231dfb
      Linus Torvalds authored
      Pull io_uring fixes from Jens Axboe:
       "One fix for a regression with poll in this merge window, and another
        just hardens the io-wq exit path a bit"
      
      * tag 'io_uring-5.13-2021-05-22' of git://git.kernel.dk/linux-block:
        io_uring: fortify tctx/io_wq cleanup
        io_uring: don't modify req->poll for rw
      b9231dfb
    • Linus Torvalds's avatar
      Merge tag 'for-linus-5.13b-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip · 23d72926
      Linus Torvalds authored
      Pull xen fixes from Juergen Gross:
      
       - a fix for a boot regression when running as PV guest on hardware
         without NX support
      
       - a small series fixing a bug in the Xen pciback driver when
         configuring a PCI card with multiple virtual functions
      
      * tag 'for-linus-5.13b-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
        xen-pciback: reconfigure also from backend watch handler
        xen-pciback: redo VF placement in the virtual topology
        x86/Xen: swap NX determination and GDT setup on BSP
      23d72926
    • Linus Torvalds's avatar
      Merge tag 'xfs-5.13-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux · a3969ef4
      Linus Torvalds authored
      Pull xfs fixes from Darrick Wong:
      
       - Fix some math errors in the realtime allocator when extent size hints
         are applied.
      
       - Fix unnecessary short writes to realtime files when free space is
         fragmented.
      
       - Fix a crash when using scrub tracepoints.
      
       - Restore ioctl uapi definitions that were accidentally removed in
         5.13-rc1.
      
      * tag 'xfs-5.13-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
        xfs: restore old ioctl definitions
        xfs: fix deadlock retry tracepoint arguments
        xfs: retry allocations when locality-based search fails
        xfs: adjust rt allocation minlen when extszhint > rtextsize
      a3969ef4
  5. 21 May, 2021 1 commit