From: Hao_Xu <haoxu@linux.alibaba.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>,
io-uring@vger.kernel.org, linux-mm@kvack.org,
Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH RFC] mm: fix the sync buffered read to the old way
Date: Thu, 22 Oct 2020 22:55:36 +0800 [thread overview]
Message-ID: <a583f28c-2066-76db-c6c8-7b2a49cc5e4d@linux.alibaba.com> (raw)
In-Reply-To: <20201022141037.GS20115@casper.infradead.org>
在 2020/10/22 下午10:10, Matthew Wilcox 写道:
> On Thu, Oct 22, 2020 at 09:58:34PM +0800, Hao Xu wrote:
>> The commit 324bcf54c449 changed the code path of async buffered reads
>> to go with the page_cache_sync_readahead() way when readahead is
>> disabled, meanwhile the sync buffered reads are forced to do IO in the
>> above way as well, which makes it go to a more complex code path.
>
> But ->readpage is (increasingly) synchronous while readahead should be
> used to start async I/Os. I'm pretty sure Jens meant to do exactly what
> he did.
Yes, we should start async I/Os with readahead, but why should we do the
sync I/O like syscall read() in this way too when ra->ra_pages is 0?
>
prev parent reply other threads:[~2020-10-22 14:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-22 13:58 Hao Xu
2020-10-22 14:10 ` Matthew Wilcox
2020-10-22 14:55 ` Hao_Xu [this message]
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