Re: [PATCH 00/14] GFS
From: Arjan van de Ven
Date: Thu Aug 11 2005 - 02:02:59 EST
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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