From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Philipp Reisner To: "Jacobson" Date: Thu, 2 Nov 2006 09:57:05 +0100 References: <200610241508.49069.philipp.reisner@linbit.com> <004101c6fca1$1593f4b0$04710a0a@jacobson> In-Reply-To: <004101c6fca1$1593f4b0$04710a0a@jacobson> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Message-Id: <200611020957.06404.philipp.reisner@linbit.com> Cc: drbd-dev@lists.linbit.com Subject: [Drbd-dev] Re: question about drbd List-Id: Coordination of development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Am Dienstag, 31. Oktober 2006 05:00 schrieb Jacobson: > Dear philipp: > I am now studying drbd code. I can not get why, in function > _drbd_send_page(), the page send method can not be used in case of > PageSlab(page) =3D=3D 1? I am looking forword to your response:). Many th= anks. > one of drbd fan If I remeber correctly, pages that are controlled by slab have only a use count of one (Slab holds that single reference) [maybe it was zero, because slab does not use the reference counting on pages]. When zero copy send is done, the network code simply decreases the reference count to that page by one.=20 I think it was the slab code that does not like it if someone=20 modifies the reference counts of the pages with are owned by=20 slab. PS: As noted in the code, the only FS at that time, was XFS, which=20 was using such pages... =2DPhil =2D-=20 : Dipl-Ing Philipp Reisner Tel +43-1-8178292-50 : : LINBIT Information Technologies GmbH Fax +43-1-8178292-82 : : Sch=F6nbrunnerstr 244, 1120 Vienna, Austria http://www.linbit.com :