From: Andreas Dilger Subject: Re: [PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if huge page cache enabled Date: Tue, 25 Oct 2016 22:13:13 -0600 Message-ID: References: <20161025001342.76126-1-kirill.shutemov@linux.intel.com> <20161025001342.76126-19-kirill.shutemov@linux.intel.com> <20161025072122.GA21708@infradead.org> <20161025125431.GA22787@node.shutemov.name> Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Content-Type: multipart/signed; boundary="Apple-Mail=_5A8DFCBE-21B1-4B71-A2A9-6CB060976717"; protocol="application/pgp-signature"; micalg=pgp-sha256 Cc: Christoph Hellwig , "Kirill A. Shutemov" , Theodore Ts'o , Andreas Dilger , Jan Kara , Andrew Morton , Alexander Viro , Hugh Dickins , Andrea Arcangeli , Dave Hansen , Vlastimil Babka , Matthew Wilcox , Ross Zwisler , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org To: "Kirill A. Shutemov" Return-path: In-Reply-To: <20161025125431.GA22787@node.shutemov.name> Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org --Apple-Mail=_5A8DFCBE-21B1-4B71-A2A9-6CB060976717 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii On Oct 25, 2016, at 6:54 AM, Kirill A. Shutemov wrote: > > On Tue, Oct 25, 2016 at 12:21:22AM -0700, Christoph Hellwig wrote: >> 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. > > The size of required pool depends on architecture: different architectures > has different (huge page size)/(base page size). > > Would it be okay if I add one more pool with size equal to HPAGE_PMD_NR, > if it's bigger than than BIO_MAX_PAGES and huge pages are enabled? Why wouldn't you have all the pool sizes in between? Definitely 1MB has been too small already for high-bandwidth IO. I wouldn't mind BIOs up to 4MB or larger since most high-end RAID hardware does best with 4MB IOs. Cheers, Andreas --Apple-Mail=_5A8DFCBE-21B1-4B71-A2A9-6CB060976717 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQIVAwUBWBAtWnKl2rkXzB/gAQi8tA/+IKGZ0QC1GIU3Y5HRATtiqNxImtCde9PD IzQe3/7A+ohno8h3xarTqHJhTNLDKnd6u+ARqcbjaqxWQkDfee8QHVU5T/R5GLU/ TWmdYeBKGYffejgBBNy1MCuU7l72gUlHiCS0+m5kY0YhMoNwarRyb5hVLJk6y1Og uTWwlCJV9kz+GVz/Nc+Tk83v3oJy6Zon2o19L6iP/PrcRGTqHXhbvyJ8zdbs4aDc MM34IBv585W961LF9VWBfCd0+cDtv/Q0Smsjv9p67xQZoWMfC9R2QzPAu5tWpawa Q49D7sh9LXnRcqVXgHmt/4oCUcw/f1bLZ7I8pfaT0sooIC7hcsu1XpempADDQBWI ghE1Gx1eMCWGreY5VfJ7bqjadh86LrtNpjHHtMUj1VmC7lwGiBnMMvIr+iFLve9q W3VxsIZC6c1Vl7O7PbKGuc2804c0zXbSNSsZg39xbjnAh1ZMeR4NqHYIpR/BXUhg nKrfWU/dLmn9j3niF6mrEmThhEgLnqqWJhVtd8X7L/ahxGVjcFlD0HnfpOB7MqKK Sh5X5lgNKrsrfkFPbLd9FWGc9NQMAq5qK1kKof1AJhLtXg3nfkV6sRon/Gzio584 7zZNi6l69kjvMRbvxKw8LTi1Mqk0k5Fohp2ljAIYZDs9E6Qk7kBTYqIPN1I/BrqP vcDB7Jjn88A= =sSD6 -----END PGP SIGNATURE----- --Apple-Mail=_5A8DFCBE-21B1-4B71-A2A9-6CB060976717-- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org