From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Kirill A. Shutemov" Subject: PAGE_CACHE_SIZE vs. PAGE_SIZE Date: Fri, 18 Jan 2013 17:57:25 +0200 Message-ID: <20130118155724.GA8507@otc-wbsnb-06> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="LZvS9be/3tNcYl/X" Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Wu Fengguang , Jan Kara , Nick Piggin , Andrea Arcangeli , Andi Kleen , "Kirill A. Shutemov" To: Andrew Morton , Linus Torvalds , Al Viro Return-path: Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org --LZvS9be/3tNcYl/X Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, PAGE_CACHE_* macros were introduced long time ago in hope to implement page cache with larger chunks than one page in future. In fact it was never done. Some code paths assume PAGE_CACHE_SIZE <=3D PAGE_SIZE. E.g. we use zero_user_segments() to clear stale parts of page on cache filling, but the function is implemented only for individual small page. It's unlikely that global switch to PAGE_CACHE_SIZE > PAGE_SIZE will never happen since it will affect to much code at once. I think support of larger chunks in page cache can be in implemented in some form of THP with per-fs enabling. Is it time to get rid of PAGE_CACHE_* macros? I can prepare patchset if it's okay. --=20 Kirill A. Shutemov --LZvS9be/3tNcYl/X Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJQ+XDkAAoJEAd+omnVudOMzKgP/2i22lky6JJInM7MxXkJFZ1l /pksssQ6hdHdb+B0QCBjoUDw/ZAUessm0/aDrBwjTmfAGoUbnIWQZf90Hf/ybNV8 e5gh8n73XXVr7irhUJB/7jJPOfMMdU2yw0g3cfr6MC9bzvzt9V8dWmyGnIvUPthG ZKtwH/Aj2VqkVg7My+Kucy+bM/VT3XwPtVG7CMbk1wpW9TkRWxVBbfQZdxuGHAzC 5dyagwKYltpc9N6zb0WUwmE3HFT1LEKDGdzA3Re20rZSgTcWY2hrrHQQARDVLfyc SWPaqhXDuKPh9iWn75yJPwvPXv+x/ME6wnh43k8wzX5dSXorohDARO1+Csc+3IJb tk/sDJK85198Hnpkg0IZE+rfSc+Y18Yy+cYch4nuTYn1BwLWNE6B/2ZaVc/vSbU/ lGD6HLCOtH9sOx/nQ+oopj0swcPXKsGxTV/lfqazPEeASmdVTA2XS99ArFl/Mp71 qTvYgxlp4Nn8+3CgvMwHZQUbW02Xo5RFd9SdaPyhF0kXmbWhnpxFk5N9Hsy70xG4 o7/f6psrC4XkSN8DlHw/2hT32OSrgmnFmttg8L6mcYN6E6cQY8/pJI2WDIGcq8uN vf8/PzVT/A/NySXrQQkCZNtYmhEW1f/k+NtBJHHuY1nr7qky+uKUM0GJmppW310k VvAC0r7ef7e8jEFAq43y =YqYo -----END PGP SIGNATURE----- --LZvS9be/3tNcYl/X-- -- 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