Messages in this thread | | | Date | Mon, 28 Aug 2006 22:13:45 +0530 | From | Dipankar Sarma <> | Subject | Re: [PATCH 0/4] RCU: various merge candidates |
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On Mon, Aug 28, 2006 at 06:33:09PM +0200, Arjan van de Ven wrote: > On Mon, 2006-08-28 at 21:59 +0530, Dipankar Sarma wrote: > > On Mon, Aug 28, 2006 at 06:15:48PM +0200, Arjan van de Ven wrote: > > > On Mon, 2006-08-28 at 21:38 +0530, Dipankar Sarma wrote: > > Hi Arjan, > > > > See this for a background - http://lwn.net/Articles/129511/ > > > > Primarily, rcupreempt allows read-side critical sections to > > be preempted unline classic RCU currently in mainline. It is > > also a bit more aggressive in terms of grace periods by counting > > the number of readers as opposed to periodic checks in classic > > RCU. > > > > hi, > > thanks for the explenation, this for sure explains one half of the > equation; the other half is ... "why do we not always want this"?
It comes with read-side overheads for keeping track of critical sections and we need to carefully check its impact on performance over a more wide variety of workload before deciding to switch the default.
See table 2 of page 10 in this paper -
http://www.rdrop.com/users/paulmck/RCU/OLSrtRCU.2006.08.11a.pdf
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