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Date: Tue, 25 Oct 2016 00:21:22 -0700
From: Christoph Hellwig <hch@infradead.org>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>, Jan Kara <jack@suse.com>,
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Subject: Re: [PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if
 huge page cache enabled
Message-ID: <20161025072122.GA21708@infradead.org>
References: <20161025001342.76126-1-kirill.shutemov@linux.intel.com>
 <20161025001342.76126-19-kirill.shutemov@linux.intel.com>
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On Tue, Oct 25, 2016 at 03:13:17AM +0300, Kirill A. Shutemov wrote:
> We are going to do IO a huge page a time. So we need BIO_MAX_PAGES to be
> at least HPAGE_PMD_NR. For x86-64, it's 512 pages.

NAK.  The maximum bio size should not depend on an obscure vm config,
please send a standalone patch increasing the size to the block list,
with a much long explanation.  Also you can't simply increase the size
of the largers pool, we'll probably need more pools instead, or maybe
even implement a similar chaining scheme as we do for struct
scatterlist.