Re: [RFC] what to do with IOCB_DSYNC?

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 12:48:20 -0600	[thread overview]
Message-ID: <737a889f-93b9-039f-7708-c15a21fbca2a@kernel.dk> (raw)
In-Reply-To: <YoqDTV9sa4k9b9nb@zeniv-ca.linux.org.uk>

On 5/22/22 12:39 PM, Al Viro wrote:
> On Sun, May 22, 2022 at 12:29:16PM -0600, Jens Axboe wrote:
>> It was sent out as a discussion point, it's not a submission and it's by
>> no means complete (as mentioned!). If you're working on this, I'd be
>> happy to drop it, it's not like I really enjoy the iov_iter code... And
>> it sounds like you are?
> 
> *snort*
> 
> Yes, I am working on it.  As for enjoying that thing...  I'm not fond of

OK great, I'll abandon this sandbox. Let me know when you have something
to test, and I can compare some numbers between non-iter, iter,
iter-with-ubuf.

> forests of macros, to put it mildly.  Even in the trimmed form it still
> stinks, and places like copy_page_to_iter for iovec are still fucking
> awful wrt misguided microoptimization attempts - mine, at that, so I've
> nobody else to curse ;-/

And it's not even clear which ones won't work with the generic variants,
and which ones are just an optimization. I suspect a lot of the icache
bloat from this just makes things worse...

-- 
Jens Axboe