Re: [RFC] Bypass filesystems for reading cached pages

2020-07-02 Thread Matthew Wilcox
On Thu, Jul 02, 2020 at 05:16:43PM +0200, Andreas Gruenbacher wrote: > On Wed, Jun 24, 2020 at 2:35 PM Andreas Gruenbacher > wrote: > > On Mon, Jun 22, 2020 at 8:13 PM Matthew Wilcox wrote: > > > On Mon, Jun 22, 2020 at 04:35:05PM +0200, Andreas Gruenbacher wrote: > > > > I'm fine with not movin

Re: [RFC] Bypass filesystems for reading cached pages

2020-07-02 Thread Andreas Gruenbacher
On Wed, Jun 24, 2020 at 2:35 PM Andreas Gruenbacher wrote: > On Mon, Jun 22, 2020 at 8:13 PM Matthew Wilcox wrote: > > On Mon, Jun 22, 2020 at 04:35:05PM +0200, Andreas Gruenbacher wrote: > > > I'm fine with not moving that functionality into the VFS. The problem > > > I have in gfs2 is that taki

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-24 Thread Andreas Gruenbacher
On Mon, Jun 22, 2020 at 8:13 PM Matthew Wilcox wrote: > On Mon, Jun 22, 2020 at 04:35:05PM +0200, Andreas Gruenbacher wrote: > > I'm fine with not moving that functionality into the VFS. The problem > > I have in gfs2 is that taking glocks is really expensive. Part of that > > overhead is accident

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-23 Thread Andreas Gruenbacher
On Tue, Jun 23, 2020 at 2:52 AM Dave Chinner wrote: > On Mon, Jun 22, 2020 at 04:35:05PM +0200, Andreas Gruenbacher wrote: > > On Mon, Jun 22, 2020 at 2:32 AM Dave Chinner wrote: > > > On Fri, Jun 19, 2020 at 08:50:36AM -0700, Matthew Wilcox wrote: > > > > > > > > This patch lifts the IOCB_CACHED

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-22 Thread Dave Chinner
On Mon, Jun 22, 2020 at 08:18:57PM +0100, Matthew Wilcox wrote: > On Mon, Jun 22, 2020 at 10:32:15AM +1000, Dave Chinner wrote: > > On Fri, Jun 19, 2020 at 08:50:36AM -0700, Matthew Wilcox wrote: > > > > > > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > > > The advantage

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-22 Thread Dave Chinner
On Mon, Jun 22, 2020 at 04:35:05PM +0200, Andreas Gruenbacher wrote: > On Mon, Jun 22, 2020 at 2:32 AM Dave Chinner wrote: > > On Fri, Jun 19, 2020 at 08:50:36AM -0700, Matthew Wilcox wrote: > > > > > > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > > > The advantage of t

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-22 Thread Matthew Wilcox
On Mon, Jun 22, 2020 at 10:32:15AM +1000, Dave Chinner wrote: > On Fri, Jun 19, 2020 at 08:50:36AM -0700, Matthew Wilcox wrote: > > > > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > > The advantage of this patch is that we can avoid taking any filesystem > > lock, as lon

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-22 Thread Matthew Wilcox
On Mon, Jun 22, 2020 at 04:35:05PM +0200, Andreas Gruenbacher wrote: > I'm fine with not moving that functionality into the VFS. The problem > I have in gfs2 is that taking glocks is really expensive. Part of that > overhead is accidental, but we definitely won't be able to fix it in > the short te

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-22 Thread Andreas Gruenbacher
On Mon, Jun 22, 2020 at 2:32 AM Dave Chinner wrote: > On Fri, Jun 19, 2020 at 08:50:36AM -0700, Matthew Wilcox wrote: > > > > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > > The advantage of this patch is that we can avoid taking any filesystem > > lock, as long as the p

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-21 Thread Dave Chinner
On Sat, Jun 20, 2020 at 12:15:21PM -0700, Matthew Wilcox wrote: > On Sat, Jun 20, 2020 at 09:19:37AM +0300, Amir Goldstein wrote: > > On Fri, Jun 19, 2020 at 6:52 PM Matthew Wilcox wrote: > > > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > > > The advantage of this patch

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-21 Thread Dave Chinner
On Fri, Jun 19, 2020 at 08:50:36AM -0700, Matthew Wilcox wrote: > > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > The advantage of this patch is that we can avoid taking any filesystem > lock, as long as the pages being accessed are in the cache (and we don't > need to r

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-20 Thread Amir Goldstein
[CC: Dave Chinner, Jan Kara, xfs] On Sat, Jun 20, 2020 at 10:15 PM Matthew Wilcox wrote: > > On Sat, Jun 20, 2020 at 09:19:37AM +0300, Amir Goldstein wrote: > > On Fri, Jun 19, 2020 at 6:52 PM Matthew Wilcox wrote: > > > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > >

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-20 Thread Matthew Wilcox
On Sat, Jun 20, 2020 at 09:19:37AM +0300, Amir Goldstein wrote: > On Fri, Jun 19, 2020 at 6:52 PM Matthew Wilcox wrote: > > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > > The advantage of this patch is that we can avoid taking any filesystem > > lock, as long as the pag

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-19 Thread Amir Goldstein
On Fri, Jun 19, 2020 at 6:52 PM Matthew Wilcox wrote: > > > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > The advantage of this patch is that we can avoid taking any filesystem > lock, as long as the pages being accessed are in the cache (and we don't > need to readahead

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-19 Thread Chaitanya Kulkarni
Matthew, On 6/19/20 1:12 PM, Matthew Wilcox wrote: > On Fri, Jun 19, 2020 at 07:06:19PM +, Chaitanya Kulkarni wrote: >> On 6/19/20 8:50 AM, Matthew Wilcox wrote: >>> This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. >>> The advantage of this patch is that we can avoid taki

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-19 Thread Matthew Wilcox
On Fri, Jun 19, 2020 at 07:06:19PM +, Chaitanya Kulkarni wrote: > On 6/19/20 8:50 AM, Matthew Wilcox wrote: > > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > > The advantage of this patch is that we can avoid taking any filesystem > > lock, as long as the pages being

Re: [RFC] Bypass filesystems for reading cached pages

2020-06-19 Thread Chaitanya Kulkarni
On 6/19/20 8:50 AM, Matthew Wilcox wrote: > This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. > The advantage of this patch is that we can avoid taking any filesystem > lock, as long as the pages being accessed are in the cache (and we don't > need to readahead any pages into t

[RFC] Bypass filesystems for reading cached pages

2020-06-19 Thread Matthew Wilcox
This patch lifts the IOCB_CACHED idea expressed by Andreas to the VFS. The advantage of this patch is that we can avoid taking any filesystem lock, as long as the pages being accessed are in the cache (and we don't need to readahead any pages into the cache). We also avoid an indirect function c