From: David Laight <David.Laight@ACULAB.COM>
To: 'David Howells' <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jens Axboe <axboe@kernel.dk>, "Christoph Hellwig" <hch@lst.de>,
Christian Brauner <christian@brauner.io>,
"Matthew Wilcox" <willy@infradead.org>,
Brendan Higgins <brendanhiggins@google.com>,
David Gow <davidgow@google.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>,
"kunit-dev@googlegroups.com" <kunit-dev@googlegroups.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Christian Brauner <brauner@kernel.org>,
"David Hildenbrand" <david@redhat.com>,
John Hubbard <jhubbard@nvidia.com>
Subject: RE: [RFC PATCH 9/9] iov_iter: Add benchmarking kunit tests for UBUF/IOVEC
Date: Fri, 15 Sep 2023 12:10:07 +0000 [thread overview]
Message-ID: <72e93605b28742c2a496ce4890ecaa80@AcuMS.aculab.com> (raw)
In-Reply-To: <3449352.1694776980@warthog.procyon.org.uk>
From: David Howells
> Sent: 15 September 2023 12:23
>
> David Laight <David.Laight@ACULAB.COM> wrote:
>
> > > > Some measurements can be made using readv() and writev()
> > > > on /dev/zero and /dev/null.
> > >
> > > Forget /dev/null; that doesn't actually engage any iteration code. The same
> > > for writing to /dev/zero. Reading from /dev/zero does its own iteration thing
> > > rather than using iterate_and_advance(), presumably because it checks for
> > > signals and resched.
> >
> > Using /dev/null does exercise the 'copy iov from user' code.
>
> Ummm.... Not really:
I was thinking of import_iovec() - or whatever its current
name is.
That really needs a single structure that contains the iov_iter
and the cache[] (which the caller pretty much always allocates
in the same place).
Fiddling with that is ok until you find what io_uring does.
Then it all gets entirely horrid.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2023-09-15 12:11 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-14 22:15 [RFC PATCH 0/9] iov_iter: kunit: Cleanup, abstraction and more tests David Howells
2023-09-14 22:15 ` [RFC PATCH 1/9] iov_iter: Fix some checkpatch complaints in kunit tests David Howells
2023-09-14 22:15 ` [RFC PATCH 2/9] iov_iter: Consolidate some of the repeated code into helpers David Howells
2023-09-14 22:15 ` [RFC PATCH 3/9] iov_iter: Consolidate the test vector struct in the kunit tests David Howells
2023-09-14 22:15 ` [RFC PATCH 4/9] iov_iter: Consolidate bvec pattern checking David Howells
2023-09-14 22:15 ` [RFC PATCH 5/9] iov_iter: Create a function to prepare userspace VM for UBUF/IOVEC tests David Howells
2023-09-14 22:15 ` [RFC PATCH 6/9] iov_iter: Add copy kunit tests for ITER_UBUF and ITER_IOVEC David Howells
2023-09-14 22:15 ` [RFC PATCH 7/9] iov_iter: Add extract " David Howells
2023-09-14 22:15 ` [RFC PATCH 8/9] iov_iter: Add benchmarking kunit tests David Howells
2023-09-14 22:15 ` [RFC PATCH 9/9] iov_iter: Add benchmarking kunit tests for UBUF/IOVEC David Howells
2023-09-15 7:09 ` David Laight
2023-09-15 10:10 ` David Howells
2023-09-15 10:51 ` David Laight
2023-09-15 11:23 ` David Howells
2023-09-15 12:10 ` David Laight [this message]
2023-09-15 12:36 ` David Howells
2023-09-15 13:08 ` David Laight
2023-09-15 13:24 ` David Howells
2023-09-15 12:19 ` David Howells
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