Messages in this thread | | | Date | Wed, 2 Mar 2016 16:55:04 -0500 | From | Waiman Long <> | Subject | Re: [PATCH v5 5/5] lib/percpu-list: Add a config parameter for disabling per-cpu list |
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On 03/02/2016 03:41 AM, Ingo Molnar wrote: > * Waiman Long<Waiman.Long@hpe.com> wrote: > >> As there is concern that the larger pcpu_list_node structure and the >> per-cpu overhead may be a waste of resource on small system. This patch >> adds a config parameter CONFIG_PERCPU_LIST to disable the per-cpu list >> if the kernel builder chooses to do so. With per-cpu list disabled, >> all the different groups of per-cpu lists will be degenerated into >> global lists for all the CPUs. >> >> The current default is to enable per-cpu list. A kernel builder needs >> to explicitly turn it off. >> >> Signed-off-by: Waiman Long<Waiman.Long@hpe.com> >> --- >> fs/inode.c | 2 +- >> include/linux/percpu-list.h | 93 ++++++++++++++++++++++++++++++++++++++++++- >> lib/Kconfig | 14 ++++++ >> lib/percpu-list.c | 24 +++++++++++- >> 4 files changed, 130 insertions(+), 3 deletions(-) > I think this kind of #ifdef complexity and the doubling of our Kconfig and testing > space is counterproductive, and I think the per CPU locking is a win on as small > as dual core CPUs, and on UP CPUs the per CPU list becomes a single global list > automatically. > > I'm not against visible memory savings for overly clever scalability features, but > this does not appear to be such a case, so: > > NAKed-by: Ingo Molnar<mingo@kernel.org> > > Thanks, > > Ingo
The last patch was there to answer a feedback from Jan. I am fine if that is not merged as I prefer to have the per-cpu list capability as the default anyway.
Cheers, Longman
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