This bug was fixed in the package liburcu - 0.10.1-1ubuntu1
---
liburcu (0.10.1-1ubuntu1) bionic; urgency=medium
* d/p/liburcu-use-membarrier-private-expedited.patch
* d/p/liburcu-bp-use-membarrier-private-expedited.patch
- Enable usage of MEMBARRIER_CMD_PRIVATE_EXPEDITED in t
Thank you for looking into this Matthew, Rafael and Dan! I think we have
enough understanding now to give it a shot. I would feel at ease if,
after accepting and building the package, we'd also once again sanity-
check the rdeps if they still work as expected. Anyway, accepting!
** Changed in: lib
@sil2100,
thanks for the trust. My TL;DR version for you is:
>From one of liburcu maintainers (https://github.com/compudj):
"""
Posted Nov 24, 2013 23:55 UTC (Sun) by compudj (subscriber, #43335) [Link]
Tracking threads running in multiple processes using a common shared memory is
not possible
This is a very tricky SRU to be reviewing. Not having too much expertise
in RCU, I need to rely on the opinion of people with more experience in
this regard. Performance improvements like these are certainly SRUable,
but we need to make sure that all the regression potential is covered
and behavior
> - apart from feedback given by @mruffell, to also check if any of
librcu consumers are depending on a full membarrier - driven by kernel -
for ** shared pages among different processes **
I agree with @ddstreet, I don't think liburcu gives that sort of
guarantee when it comes to cross process sy
> - apart from feedback given by @mruffell, to also check if any of
librcu consumers are depending on a full membarrier - driven by kernel -
for ** shared pages among different processes **
this is a good point, although I don't think liburcu makes guarantees
like that, for memory barriers outside
Sorry to jump in, I wrote the membarrier syscall LTP interface test
(https://github.com/linux-test-
project/ltp/blob/master/testcases/kernel/syscalls/membarrier/membarrier01.c)
when I was at Linaro and felt attracted to reading all this during my
bug triage day =).
So, for MEMBARRIER_CMD_PRIVATE_E
excellent analysis, thanks @mruffell!
uploaded to the bionic queue.
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https://bugs.launchpad.net/bugs/1876230
Title:
liburcu: Enable MEMBARRIER_CMD_PRIVATE_E
Answering question 2. I have done a comprehensive performance analysis
based on the benchmark application.
Note: The SRU changes how the sys_membarrier syscall is used. The
implementation that we want to change to in this SRU never blocks, while
the previous implementation does. This makes perform
To answer question 1, I went and checked every rdepends package:
gdnsd: dynamically links to -lurcu-qsbr
$ ldd /usr/sbin/gdnsd
liburcu-qsbr.so.6 => /usr/lib/x86_64-linux-gnu/liburcu-qsbr.so.6
(0x7f33bfde5000)
glusterfs: The only package I am not entirely sure about. Only glusterd uses
urcu:
Hi @mruffell,
two questions for this sru:
1) it looks like static libs are built/provided by this package:
$ pull-lp-debs liburcu bionic ; for p in *.deb ; do echo "$p:" ; dpkg-deb -c $p
| grep -E '*\.a' ; done
Found liburcu 0.10.1-1 in bionic
Using existing file liburcu-dev_0.10.1-1_amd64.deb
** Tags added: sts-sponsor-ddstreet
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https://bugs.launchpad.net/bugs/1876230
Title:
liburcu: Enable MEMBARRIER_CMD_PRIVATE_EXPEDITED to address
performance
** Description changed:
[Impact]
In Linux 4.3, a new syscall was defined, called "membarrier". This
systemcall was defined specifically for use in userspace-rcu (liburcu)
to speed up the fast path / reader side of the library. The original
implementation in Linux 4.3 only supported th
Attached is a debdiff for Bionic
** Patch added: "liburcu debdiff for Bionic"
https://bugs.launchpad.net/ubuntu/+source/liburcu/+bug/1876230/+attachment/5364290/+files/lp1876230_bionic.debdiff
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