linux-kernel - Re: [PATCH, v2] PCI: create function symlinks in /sys/bus/pci/slots/N/

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Message-ID: <20080823200446.GA24936@ldl.fc.hp.com>
Date:	Sat, 23 Aug 2008 14:04:46 -0600
From:	Alex Chiang <achiang@...com>
To:	Greg KH <greg@...ah.com>
Cc:	Matthew Wilcox <matthew@....cx>, jbarnes@...tuousgeek.org,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH, v2] PCI: create function symlinks in
	/sys/bus/pci/slots/N/

* Greg KH <greg@...ah.com>:
> On Fri, Aug 22, 2008 at 01:53:58PM -0600, Alex Chiang wrote:
> > 
> > Does anyone have numbers for how much it costs to create a new
> > symlink? I could try and figure this out but it will take a few
> > days (busy with other stuff).
> 
> Almost nothing.
> 
> sysfs creates these things on the fly as they are accessed, and if
> memory pressure on the machine happens, they are freed up properly and
> then created again if a user asks to see them in the tree.
> 
> So don't worry about memory issues when adding new files or symlinks in
> sysfs, it just isn't a problem (we handle 20000 disks easily on low
> memory 31bit s390 systems.)

Great, thanks for the explanation.  I've heard the "memory
overhead" argument before for not wanting to create other sysfs
files/links, so this will be good to debunk that bogeyman if it
pops up again in the future.

Did you get a chance to take a look at the documentation I wrote
for these new symlinks? [I also went and documented the existing
slots/ directory as well...]

Was it what you had in mind?

Thanks.

/ac

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