From: Peter Oskolkov <posk@posk.io>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org
Cc: Paul Turner <pjt@google.com>, Ben Segall <bsegall@google.com>,
Peter Oskolkov <posk@google.com>, Peter Oskolkov <posk@posk.io>,
Joel Fernandes <joel@joelfernandes.org>,
Andrei Vagin <avagin@google.com>,
Jim Newsome <jnewsome@torproject.org>,
Jann Horn <jannh@google.com>
Subject: [RFC PATCH 0/3 v0.2] RFC: sched/UMCG
Date: Thu, 8 Jul 2021 12:46:35 -0700 [thread overview]
Message-ID: <20210708194638.128950-1-posk@google.com> (raw)
This is another attempt at implementing UMCG, based on
discussion in https://lore.kernel.org/patchwork/cover/1433967/
Most of the "why" is covered here (some details are obsolete):
https://lore.kernel.org/patchwork/cover/1433967/#1632328
At a high level, UMCG servers/workers provide the foundation
for an M:N threading library, as described in the link above.
In addition, servers without workers can be used as "basic"
UMCG tasks if wait/wake/context-switch are the only desired
operations.
Joel Fernandes has also once mentioned that he had a use case
for a wake+bring-the-wakee-to-the-current-CPU operation,
so this is now also supported via UMCG_WF_CURRENT_CPU flag
(patch 3).
Patch 1: add WF_CURRENT_CPU and tweak ttwu - same as last time
Patch 2: add X86_64 helpers to work atomically with userspace values
Patch 3: implement UMCG kernel-side
In this version of the patchset I used only userspace/TLS
data, as suggested by Peter Zijlstra. With the exception
of one issue (see patch 3 commit message) everything seems
to be working great.
This TLS-only approach makes the userspace code a bit more
involved, so I'm not posting libumcg/selftests with this
patchset to focus on the kernel side only.
TODO:
- put atomic helpers from patch 2 into their proper place (unless
keeping them in kernel/sched/umcg.h is OK)
- fix the wake server issue in preempt disable block (see patch 3)
- implement timeout handling
- imlement worker preemption
- more testing
- manpages, docs, and similar
- attach libumbc and selftest patches
Peter Oskolkov (3):
sched: add WF_CURRENT_CPU and externise ttwu
sched/umcg: RFC: add userspace atomic helpers
sched/umcg: RFC: implement UMCG syscalls
arch/x86/entry/syscalls/syscall_64.tbl | 2 +
include/linux/sched.h | 6 +
include/linux/syscalls.h | 4 +
include/uapi/asm-generic/unistd.h | 8 +-
include/uapi/linux/umcg.h | 246 +++++++++++++
init/Kconfig | 10 +
kernel/exit.c | 7 +
kernel/sched/Makefile | 1 +
kernel/sched/core.c | 20 +-
kernel/sched/fair.c | 4 +
kernel/sched/sched.h | 15 +-
kernel/sched/umcg.c | 481 +++++++++++++++++++++++++
kernel/sched/umcg.h | 271 ++++++++++++++
kernel/sys_ni.c | 4 +
14 files changed, 1068 insertions(+), 11 deletions(-)
create mode 100644 include/uapi/linux/umcg.h
create mode 100644 kernel/sched/umcg.c
create mode 100644 kernel/sched/umcg.h
--
2.25.1
next reply other threads:[~2021-07-08 19:46 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-08 19:46 Peter Oskolkov [this message]
2021-07-08 19:46 ` [RFC PATCH 1/3 v0.2] sched: add WF_CURRENT_CPU and externise ttwu Peter Oskolkov
2021-07-08 19:46 ` [RFC PATCH 2/3 v0.2] sched/umcg: RFC: add userspace atomic helpers Peter Oskolkov
2021-07-08 21:12 ` Jann Horn
2021-07-09 4:01 ` Peter Oskolkov
2021-07-09 8:01 ` Peter Zijlstra
2021-07-09 16:57 ` Peter Oskolkov
2021-07-09 17:33 ` Peter Oskolkov
2021-07-13 16:10 ` Peter Zijlstra
2021-07-13 17:14 ` Peter Oskolkov
2021-07-08 19:46 ` [RFC PATCH 3/3 v0.2] sched/umcg: RFC: implement UMCG syscalls Peter Oskolkov
2021-07-11 16:35 ` Peter Oskolkov
2021-07-11 18:29 ` Thierry Delisle
2021-07-12 15:40 ` Peter Oskolkov
2021-07-12 21:44 ` Thierry Delisle
2021-07-12 23:31 ` Peter Oskolkov
2021-07-13 14:02 ` Peter Zijlstra
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