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From: Pavel Begunkov <[email protected]>
To: Christoph Hellwig <[email protected]>
Cc: Jens Axboe <[email protected]>,
	Alexander Viro <[email protected]>,
	[email protected], [email protected],
	[email protected], [email protected],
	Matthew Wilcox <[email protected]>,
	Johannes Weiner <[email protected]>,
	Ming Lei <[email protected]>
Subject: Re: [PATCH 2/2] block: no-copy bvec for direct IO
Date: Wed, 9 Dec 2020 12:01:27 +0000	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 09/12/2020 08:40, Christoph Hellwig wrote:
>> +	/*
>> +	 * In practice groups of pages tend to be accessed/reclaimed/refaulted
>> +	 * together. To not go over bvec for those who didn't set BIO_WORKINGSET
>> +	 * approximate it by looking at the first page and inducing it to the
>> +	 * whole bio
>> +	 */
>> +	if (unlikely(PageWorkingset(iter->bvec->bv_page)))
>> +		bio_set_flag(bio, BIO_WORKINGSET);
> 
> IIRC the feedback was that we do not need to deal with BIO_WORKINGSET
> at all for direct I/O.

I was waiting for the conversation to unfold, i.e. for Johannes to
answer. BTW, would the same (skipping BIO_WORKINGSET) stand true for
iomap?

> 
>> +	bio_set_flag(bio, BIO_NO_PAGE_REF);
>> +
>> +	iter->count = 0;
>> +	return 0;
>> +}
> 
> This helper should go into bio.c, next to bio_iov_iter_get_pages.
> And please convert the other callers of bio_iov_iter_get_pages to this
> scheme as well.

Agree. In the end I want to merge that into bio_iov_iter_get_pages().

-- 
Pavel Begunkov

  reply	other threads:[~2020-12-09 12:05 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-09  2:19 [RFC 0/2] nocopy bvec for direct IO Pavel Begunkov
2020-12-09  2:19 ` [PATCH 1/2] iov: introduce ITER_BVEC_FLAG_FIXED Pavel Begunkov
2020-12-09  8:36   ` Christoph Hellwig
2020-12-09  9:06     ` Christoph Hellwig
2020-12-09 11:54       ` Pavel Begunkov
2020-12-09 13:07     ` Al Viro
2020-12-09 13:37       ` Pavel Begunkov
2020-12-09 17:55         ` Christoph Hellwig
2020-12-09 18:24           ` Matthew Wilcox
2020-12-13 22:09             ` Pavel Begunkov
2020-12-09  2:19 ` [PATCH 2/2] block: no-copy bvec for direct IO Pavel Begunkov
2020-12-09  8:40   ` Christoph Hellwig
2020-12-09 12:01     ` Pavel Begunkov [this message]
2020-12-09 12:05       ` Christoph Hellwig
2020-12-09 12:03         ` Pavel Begunkov
2020-12-11 14:06     ` Johannes Weiner
2020-12-11 14:20       ` Pavel Begunkov
2020-12-11 15:38         ` Johannes Weiner
2020-12-11 15:47           ` Pavel Begunkov
2020-12-11 16:13             ` Johannes Weiner
2020-12-09 21:13   ` David Laight
2020-12-09  6:50 ` [RFC 0/2] nocopy " Christoph Hellwig
2020-12-09 11:54   ` Pavel Begunkov
2020-12-09 16:53 ` Jens Axboe
2020-12-13 22:03   ` Pavel Begunkov
2020-12-09 17:06 ` Al Viro

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