From: xerofoify@gmail.com (nick)
To: kernelnewbies@lists.kernelnewbies.org
Subject: Kernel Locking Question
Date: Thu, 12 Mar 2015 00:42:02 -0400 [thread overview]
Message-ID: <5501191A.7030406@gmail.com> (raw)
In-Reply-To: <7964.1426124930@turing-police.cc.vt.edu>
On 2015-03-11 09:48 PM, Valdis.Kletnieks at vt.edu wrote:
> On Wed, 11 Mar 2015 19:03:33 -0400, Nicholas Krause said:
>
>> was wondering of how this would improve file system scalability and
>> reliability if implemented in file system code for btrfs worker threads.
>
> Step 1: Figure out what locks are contended in actual systems.
> Step 2: Determine if the scope of a contended lock can be reduced.
> Step 3: ???
> Step 4: Profit!
>
> Note that improving scalability will often cause reliability issues,
> because as you decompose locks into sets of smaller locks, you increase
> the number of ways you can get it wrong. The BKL, for all its uglyness,
> was pretty hard to screw up. On the other hand, we probably would never
> have gotten rid of it if somebody hadn't put lockdep into the kernel. It
> was painful enough even with automated testing tools....
>
Thanks Valdis,
That makes sense to me. I was wondering however about the reader vs writer issues
in file systems too as this seems to me coming up a lot in btrfs and other file
systems for various reasons.
Thanks Nick
prev parent reply other threads:[~2015-03-12 4:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-11 23:03 Kernel Locking Question Nicholas Krause
2015-03-12 1:48 ` Valdis.Kletnieks at vt.edu
2015-03-12 4:42 ` nick [this message]
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