On Mon, Sep 21, 2020 at 03:44:00PM +, David Laight wrote:
> From: Al Viro
> > Sent: 21 September 2020 16:30
> >
> > On Mon, Sep 21, 2020 at 03:21:35PM +, David Laight wrote:
> >
> > > You really don't want to be looping through the array twice.
> >
> > Profiles, please.
>
> I did some p
On Mon, Sep 21, 2020 at 04:29:37PM +0100, Al Viro wrote:
> On Mon, Sep 21, 2020 at 03:21:35PM +, David Laight wrote:
>
> > You really don't want to be looping through the array twice.
>
> Profiles, please.
Given that the iov array should be cache hot I'd be surprised to
see a huge difference
From: Al Viro
> Sent: 21 September 2020 16:30
>
> On Mon, Sep 21, 2020 at 03:21:35PM +, David Laight wrote:
>
> > You really don't want to be looping through the array twice.
>
> Profiles, please.
I did some profiling of send() v sendmsg() much earlier in the year.
I can't remember the exac
On Mon, Sep 21, 2020 at 03:21:35PM +, David Laight wrote:
> You really don't want to be looping through the array twice.
Profiles, please.
> I think the 'length' check can be optimised to do something like:
> for (...) {
> ssize_t len = (ssize_t)iov[seg].iov_len;
>
From: Al Viro
> Sent: 21 September 2020 16:02
>
> On Mon, Sep 21, 2020 at 04:34:25PM +0200, Christoph Hellwig wrote:
> > From: David Laight
> >
> > This is the only direct call of rw_copy_check_uvector(). Removing it
> > will allow rw_copy_check_uvector() to be inlined into import_iovec(),
> > w
On Mon, Sep 21, 2020 at 04:34:25PM +0200, Christoph Hellwig wrote:
> From: David Laight
>
> This is the only direct call of rw_copy_check_uvector(). Removing it
> will allow rw_copy_check_uvector() to be inlined into import_iovec(),
> while only paying a minor price by setting up an otherwise un
On Mon, Sep 21, 2020 at 04:34:25PM +0200, Christoph Hellwig wrote:
> {
> - WARN_ON(direction & ~(READ | WRITE));
> + WARN_ON(direction & ~(READ | WRITE | CHECK_IOVEC_ONLY));
This is now a no-op because:
include/linux/fs.h:#define CHECK_IOVEC_ONLY -1
I'd suggest we renumber it to 2?
(RE
From: David Laight
This is the only direct call of rw_copy_check_uvector(). Removing it
will allow rw_copy_check_uvector() to be inlined into import_iovec(),
while only paying a minor price by setting up an otherwise unused
iov_iter in the process_vm_readv/process_vm_writev syscalls that aren't
