Messages in this thread | | | Subject | Re: [PATCH 00/14] GFS | From | Arjan van de Ven <> | Date | Thu, 11 Aug 2005 08:55:49 +0200 |
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On Thu, 2005-08-11 at 14:06 +0800, David Teigland wrote: > On Tue, Aug 02, 2005 at 09:45:24AM +0200, Arjan van de Ven wrote: > > > * + if (create) > > + down_write(&ip->i_rw_mutex); > > + else > > + down_read(&ip->i_rw_mutex); > > > > why do you use a rwsem and not a regular semaphore? You are aware that > > rwsems are far more expensive than regular ones right? How skewed is > > the read/write ratio? > > Rough tests show around 4/1, that high or low?
that's quite borderline; if it was my code I'd not use a rwsem for that ratio (my own rule of thumb, based on not a lot other than gut feeling) is a 10/1 ratio at minimum... but it's not so low that it screams for removing it. However.... it might well make your code a lot simpler so it might still be worth simplifying.
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