linux-kernel - Re: fuse: increase readdir() buffer size

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Message-ID: <20250328194007.4768eaf9@pumpkin>
Date: Fri, 28 Mar 2025 19:40:07 +0000
From: David Laight <david.laight.linux@...il.com>
To: Jaco Kroon <jaco@....co.za>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
 bernd.schubert@...tmail.fm, miklos@...redi.hu, rdunlap@...radead.org,
 trapexit@...wn.link
Subject: Re: fuse: increase readdir() buffer size

On Fri, 28 Mar 2025 12:15:47 +0200
Jaco Kroon <jaco@....co.za> wrote:

> Hi All,
> 
> I've not seen feedback on this, please may I get some direction on this?

The only thing I can think of is that the longer loop might affect
scheduling latencies.

	David

> 
> Kind regards,
> Jaco
> 
> On 2025/03/15 00:16, Jaco Kroon wrote:
> > This is a follow up to the attempt made a while ago.
> >
> > Whist the patch worked, newer kernels have moved from pages to folios,
> > which gave me the motivation to implement the mechanism based on the
> > userspace buffer size patch that Miklos supplied.
> >
> > That patch works as is, but I note there are changes to components
> > (overlayfs and exportfs) that I've got very little experience with, and
> > have not tested specifically here.  They do look logical.  I've marked
> > Miklos as the Author: here, and added my own Signed-off-by - I hope this
> > is correct.
> >
> > The second patch in the series implements the changes to fuse's readdir
> > in order to utilize the first to enable reading more than one page of
> > dent structures at a time from userspace, I've included a strace from
> > before and after this patch in the commit to illustrate the difference.
> >
> > To get the relevant performance on glusterfs improved (which was
> > mentioned elsewhere in the thread) changes to glusterfs to increase the
> > number of cached dentries is also required (these are pushed to github
> > but not yet merged, because similar to this patch, got stalled before
> > getting to the "ready for merge" phase even though it's operational).
> >
> > Please advise if these two patches looks good (I've only done relatively
> > basic testing now, and it's not running on production systems yet)
> >
> > Kind regards,
> > Jaco
> >  
>