From: Jens Axboe <axboe@kernel.dk>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>,
Matthew Wilcox <willy@infradead.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [RFC] what to do with IOCB_DSYNC?
Date: Sun, 22 May 2022 19:28:53 -0600 [thread overview]
Message-ID: <22de2da8-7db0-68c5-2c85-d752a67f9604@kernel.dk> (raw)
In-Reply-To: <290daf40-a5f6-01f8-0764-2f4eb96b9d40@kernel.dk>
On 5/22/22 7:22 PM, Jens Axboe wrote:
> On 5/22/22 6:42 PM, Al Viro wrote:
>> On Sun, May 22, 2022 at 02:03:35PM -0600, Jens Axboe wrote:
>>
>>> Right, I'm saying it's not _immediately_ clear which cases are what when
>>> reading the code.
>>>
>>>> up a while ago. And no, turning that into indirect calls ended up with
>>>> arseloads of overhead, more's the pity...
>>>
>>> It's a shame, since indirect calls make for nicer code, but it's always
>>> been slower and these days even more so.
>>>
>>>> Anyway, at the moment I have something that builds; hadn't tried to
>>>> boot it yet.
>>>
>>> Nice!
>>
>> Boots and survives LTP and xfstests... Current variant is in
>> vfs.git#work.iov_iter (head should be at 27fa77a9829c). I have *not*
>> looked into the code generation in primitives; the likely/unlikely on
>> those cascades of ifs need rethinking.
>
> I noticed too. Haven't fiddled much in iov_iter.c, but for uio.h I had
> the below. iov_iter.c is a worse "offender" though, with 53 unlikely and
> 22 likely annotations...
Here it is...
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 6570b688ed39..52baa3c89505 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -163,19 +163,17 @@ static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset,
static __always_inline __must_check
size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
{
- if (unlikely(!check_copy_size(addr, bytes, true)))
- return 0;
- else
+ if (check_copy_size(addr, bytes, true))
return _copy_to_iter(addr, bytes, i);
+ return 0;
}
static __always_inline __must_check
size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
{
- if (unlikely(!check_copy_size(addr, bytes, false)))
- return 0;
- else
+ if (check_copy_size(addr, bytes, false))
return _copy_from_iter(addr, bytes, i);
+ return 0;
}
static __always_inline __must_check
@@ -191,10 +189,9 @@ bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
static __always_inline __must_check
size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
{
- if (unlikely(!check_copy_size(addr, bytes, false)))
- return 0;
- else
+ if (check_copy_size(addr, bytes, false))
return _copy_from_iter_nocache(addr, bytes, i);
+ return 0;
}
static __always_inline __must_check
--
Jens Axboe
next prev parent reply other threads:[~2022-05-23 1:29 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-21 0:46 [RFC] what to do with IOCB_DSYNC? Al Viro
2021-06-21 13:59 ` Christoph Hellwig
2021-06-21 14:03 ` Matthew Wilcox
2021-06-21 14:09 ` Christoph Hellwig
2021-06-21 14:16 ` Matthew Wilcox
2021-06-21 14:22 ` Christoph Hellwig
2021-06-21 14:32 ` Al Viro
2021-06-21 14:35 ` Christoph Hellwig
2021-06-21 15:22 ` Jens Axboe
2022-05-21 17:48 ` Al Viro
2022-05-21 19:03 ` Jens Axboe
2022-05-21 22:14 ` Jens Axboe
2022-05-22 7:45 ` Christoph Hellwig
2022-05-22 10:23 ` Matthew Wilcox
2022-05-22 10:36 ` Al Viro
2022-05-22 11:15 ` Matthew Wilcox
2022-05-22 11:45 ` Christoph Hellwig
2022-05-22 12:39 ` Jens Axboe
2022-05-22 12:48 ` Al Viro
2022-05-22 13:02 ` Jens Axboe
2022-05-22 13:07 ` Al Viro
2022-05-22 13:09 ` Jens Axboe
2022-05-22 18:06 ` Jens Axboe
2022-05-22 18:25 ` Al Viro
2022-05-22 18:29 ` Jens Axboe
2022-05-22 18:39 ` Al Viro
2022-05-22 18:48 ` Jens Axboe
2022-05-22 19:04 ` Al Viro
2022-05-22 20:03 ` Jens Axboe
2022-05-23 0:42 ` Al Viro
2022-05-23 1:22 ` Jens Axboe
2022-05-23 1:28 ` Jens Axboe [this message]
2022-05-23 1:50 ` Jens Axboe
2022-05-23 2:43 ` Jens Axboe
2022-05-23 14:22 ` Al Viro
2022-05-23 14:34 ` Jens Axboe
2022-05-23 14:47 ` Al Viro
2022-05-23 15:12 ` Jens Axboe
2022-05-23 15:44 ` Jens Axboe
2022-05-23 15:49 ` Matthew Wilcox
2022-05-23 15:55 ` Jens Axboe
2022-05-23 16:03 ` Jens Axboe
2022-05-26 14:46 ` Jason A. Donenfeld
2022-05-27 10:09 ` Ingo Molnar
2022-05-27 10:15 ` Jason A. Donenfeld
2022-05-27 14:45 ` Samuel Neves
2022-05-27 10:25 ` Ingo Molnar
2022-05-27 10:36 ` Borislav Petkov
2022-05-28 20:54 ` Sedat Dilek
2022-05-28 20:38 ` Sedat Dilek
2022-05-28 20:39 ` Sedat Dilek
2022-05-23 16:15 ` Al Viro
2022-05-25 14:34 ` Matthew Wilcox
2022-05-26 23:19 ` Al Viro
2022-05-27 14:51 ` Jens Axboe
2022-05-22 12:21 ` Al Viro
2022-05-22 7:43 ` Christoph Hellwig
2022-05-22 12:41 ` Al Viro
2022-05-22 12:51 ` Christoph Hellwig
2021-06-21 14:22 ` Al Viro
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