This bug was fixed in the package linux - 4.15.0-51.55
---------------
linux (4.15.0-51.55) bionic; urgency=medium
* linux: 4.15.0-51.55 -proposed tracker (LP: #1829219)
* disable a.out support (LP: #1818552)
- [Config] Disable a.out support
* [UBUNTU] qdio: clear intparm during shutdown (LP: #1828394)
- s390/qdio: clear intparm during shutdown
* ftrace in ubuntu_kernel_selftests hang with Cosmic kernel (LP: #1826385)
- kprobes/x86: Fix instruction patching corruption when copying more than
one
RIP-relative instruction
* touchpad not working on lenovo yoga 530 (LP: #1787775)
- Revert "UBUNTU: SAUCE: i2c:amd Depends on ACPI"
- Revert "UBUNTU: SAUCE: i2c:amd move out pointer in union i2c_event_base"
- Revert "UBUNTU: SAUCE: i2c:amd I2C Driver based on PCI Interface for
upcoming platform"
- i2c: add helpers to ease DMA handling
- i2c: add a message flag for DMA safe buffers
- i2c: add extra check to safe DMA buffer helper
- i2c: Add drivers for the AMD PCIe MP2 I2C controller
- [Config] Update config for AMD MP2 I2C driver
- [Config] Update I2C_AMD_MP2 annotations
* tm-unavailable in powerpc/tm failed on Bionic Power9 (LP: #1813129)
- selftests/powerpc: Check for pthread errors in tm-unavailable
- selftests/powerpc: Skip tm-unavailable if TM is not enabled
* cp_abort in powerpc/context_switch from ubunut_kernel_selftests failed on
Bionic P9 (LP: #1813134)
- selftests/powerpc: Remove redundant cp_abort test
* bionic/linux: completely remove snapdragon files from sources (LP: #1827880)
- [Packaging] remove snapdragon dead files
- [Config] update configs after snapdragon removal
* The noise keeps occurring when Headset is plugged in on a Dell machine
(LP: #1827972)
- ALSA: hda/realtek - Fixed Dell AIO speaker noise
* Geneve tunnels don't work when ipv6 is disabled (LP: #1794232)
- geneve: correctly handle ipv6.disable module parameter
* There are 4 HDMI/Displayport audio output listed in sound setting without
attach any HDMI/DP monitor (LP: #1827967)
- ALSA: hda/hdmi - Read the pin sense from register when repolling
- ALSA: hda/hdmi - Consider eld_valid when reporting jack event
* Headphone jack switch sense is inverted: plugging in headphones disables
headphone output (LP: #1824259)
- ASoC: rt5645: Headphone Jack sense inverts on the LattePanda board
* CTAUTO:DevOps:860.50:devops4fp1:Error occurred during LINUX Dmesg error
Checking for all LINUX clients for devops4p10 (LP: #1766201)
- SAUCE: integrity: downgrade error to warning
* Screen freeze after resume from S3 when HDMI monitor plugged on Dell
Precision 7740 (LP: #1825958)
- PCI: Restore resized BAR state on resume
* potential memory corruption on arm64 on dev release (LP: #1827437)
- driver core: Postpone DMA tear-down until after devres release
* powerpc/pmu/ebb test in ubuntu_kernel_selftest failed with "error while
loading shared libraries" on Bionic/Cosmic PowerPC (LP: #1812805)
- selftests/powerpc/pmu: Link ebb tests with -no-pie
* unnecessary request_queue freeze (LP: #1815733)
- block: avoid setting nr_requests to current value
- block: avoid setting none scheduler if it's already none
* Kprobe event string type argument failed in ftrace from
ubuntu_kernel_selftests on B/C i386 (LP: #1825780)
- selftests/ftrace: Fix kprobe string testcase to not probe notrace function
* hns: fix socket accounting (LP: #1826911)
- net: hns: fix skb->truesize underestimation
* False positive test result in run_netsocktests from net in
ubuntu_kernel_selftest (LP: #1825777)
- selftests/net: correct the return value for run_netsocktests
-- Kleber Sacilotto de Souza <kleber.so...@canonical.com> Wed, 15 May
2019 14:48:35 +0200
** Changed in: linux (Ubuntu Bionic)
Status: Fix Committed => Fix Released
** Changed in: linux (Ubuntu Cosmic)
Status: Fix Committed => Fix Released
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https://bugs.launchpad.net/bugs/1815733
Title:
unnecessary request_queue freeze
Status in linux package in Ubuntu:
Fix Released
Status in linux-oem package in Ubuntu:
Fix Released
Status in linux source package in Bionic:
Fix Released
Status in linux-oem source package in Bionic:
Fix Released
Status in linux source package in Cosmic:
Fix Released
Status in linux-oem source package in Cosmic:
Fix Released
Status in linux source package in Disco:
Fix Released
Status in linux-oem source package in Disco:
Fix Released
Bug description:
Hi all,
In linux-4.15, which is used as hwe-edge in xenial, there's an unexpected
behavior. It results in latency spikes of generic_make_request() function call.
How to reproduce:
1. Run fio:
fio --name=test --rw=randwrite --direct=1 --filename=/dev/sdt --iodepth=1
--fsync=1 --ioengine=libaio --write_lat_log loglat
2. While fio is writing to the device, change nr_requests setting to the
same value as current:
echo 256 > /sys/block/sdt/queue/nr_requests
or: if scheduler is already none:
echo none > /sys/block/sdt/queue/scheduler
3. Stop fio and check slat log:
...
3980, 16, 1, 4096
3999, 17, 1, 4096
4010, 19, 1, 4096
4020, 18, 1, 4096
4045, 10821, 1, 4096
4054, 25, 1, 4096
4070, 12, 1, 4096
4083, 17, 1, 4096
4094, 16, 1, 4096
4111, 17, 1, 4096
...
There're a few patches to fix this behavior:
https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?h=for-5.1/block&id=e5fa81408fb43ebabde65938ef8b20ae879017e7
https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?h=for-5.1/block&id=fbd72127c975dc8e532ecc73d52f3b1b00935bec
This behavior affects production systems, because every change uevent
triggers udev to change settings prior to udev rules. Some software,
for example arcconf (tool for managing adaptec HBA adapters) triggers
uevents for every block device. So, every call to arcconf utility
results in latency spike.
Could this be backported to 4.15 kernel for xenial/bionic?
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