Re: [PATCH net-next 3/6] sunrpc: Use sendmsg(MSG_SPLICE_PAGES) rather then sendpage

From: Jeff Layton
Date: Fri Aug 11 2023 - 19:07:55 EST


On Fri, 2023-08-11 at 18:50 -0400, Jeff Layton wrote:
> On Fri, 2023-06-09 at 11:02 +0100, David Howells wrote:
> > When transmitting data, call down into TCP using sendmsg with
> > MSG_SPLICE_PAGES to indicate that content should be spliced rather than
> > performing sendpage calls to transmit header, data pages and trailer.
> >
> > Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> > Acked-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> > cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> > cc: Anna Schumaker <anna@xxxxxxxxxx>
> > cc: Jeff Layton <jlayton@xxxxxxxxxx>
> > cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> > cc: Eric Dumazet <edumazet@xxxxxxxxxx>
> > cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> > cc: Paolo Abeni <pabeni@xxxxxxxxxx>
> > cc: Jens Axboe <axboe@xxxxxxxxx>
> > cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> > cc: linux-nfs@xxxxxxxxxxxxxxx
> > cc: netdev@xxxxxxxxxxxxxxx
> > ---
> > include/linux/sunrpc/svc.h | 11 +++++------
> > net/sunrpc/svcsock.c | 38 ++++++++++++--------------------------
> > 2 files changed, 17 insertions(+), 32 deletions(-)
> >
>
> I'm seeing a regression in pynfs runs with v6.5-rc5. 3 tests are failing
> in a similar fashion. WRT1b is one of them
>
> [vagrant@jlayton-kdo-nfsd nfs4.0]$ ./testserver.py --rundeps --maketree --uid=0 --gid=0 localhost:/export/pynfs/4.0/ WRT1b
> **************************************************
> WRT1b st_write.testSimpleWrite2 : FAILURE
> READ returned
> b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
> expected b'\x00\x00\x00\x00\x00write data'
> INIT st_setclientid.testValid : PASS
> MKFILE st_open.testOpen : PASS
> **************************************************
> Command line asked for 3 of 679 tests
> Of those: 0 Skipped, 1 Failed, 0 Warned, 2 Passed

FWIW, here's a capture that shows the problem. See frames 109-112 in
particular. If no one has thoughts on this one, I'll plan to have a look
early next week.

Thanks,
--
Jeff Layton <jlayton@xxxxxxxxxx>

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