From: Uladzislau Rezki <urezki@gmail.com>
To: George Spelvin <lkml@SDF.ORG>
Cc: Uladzislau Rezki <urezki@gmail.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
rcu@vger.kernel.org, josh@joshtriplett.org, rostedt@goodmis.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
joel@joelfernandes.org
Subject: Re: Is there a reason we don't have kvfree_rcu()?
Date: Fri, 13 Mar 2020 14:44:34 +0100 [thread overview]
Message-ID: <20200313134434.GB28457@pc636> (raw)
In-Reply-To: <20200313050659.GA22938@SDF.ORG>
On Fri, Mar 13, 2020 at 05:06:59AM +0000, George Spelvin wrote:
> I'd just like to mention that the is_vmalloc_addr() test depends only on
> the virtual address, so can be done when the memory is queued, before the
> grace period. That is, you could have kfree_rcu(), vfree_rcu(), and a
> kvfree_rcu() function which decides between them.
>
> One advantage of that would be that you could put the vfree() sanity
> checks into vfree_rcu(), so errors would have a useful backtrace,
> and just do the __vunmap when the grace period expires.
>
> Or you could build a mixed queue and do the is_vmalloc_addr() test at
> the end of the grace period. That was my original idea, because it
> avoids the need for a separate queue. (In the _rcu_bulk_data structure,
> you can do a quicksort-style partitioning on is_vmalloc_addr(), so
> the kfree_bulk() pointers are all contiguous.)
>
> Just an implementation option.
Thanks for your input. Mixed queue would require sorting, one node can
contain up to ~509 elements if PAGE_SIZE is 4096, so i am not sure how
it would impact performance under heavy load. But anyway, thanks again.
--
Vlad Rezki
next prev parent reply other threads:[~2020-03-13 13:44 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-12 16:27 Is there a reason we don't have kvfree_rcu()? George Spelvin
2020-03-12 18:11 ` Paul E. McKenney
2020-03-12 19:10 ` Uladzislau Rezki
2020-03-13 3:58 ` Joel Fernandes
2020-03-13 13:21 ` Uladzislau Rezki
2020-03-13 13:40 ` Joel Fernandes
2020-03-13 5:06 ` George Spelvin
2020-03-13 13:44 ` Uladzislau Rezki [this message]
2020-03-13 13:54 ` Paul E. McKenney
2020-03-13 16:52 ` George Spelvin
2020-03-13 18:19 ` Paul E. McKenney
2020-03-13 18:46 ` George Spelvin
2020-03-13 19:58 ` Paul E. McKenney
2020-03-12 22:24 ` George Spelvin
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