From mboxrd@z Thu Jan 1 00:00:00 1970 From: Abhijith Das Date: Mon, 9 May 2016 13:48:01 -0400 (EDT) Subject: [Cluster-devel] [fsck.gfs2 v2 PATCH 00/40] fsck.gfs2: memory reduction patches In-Reply-To: References: Message-ID: <2033126818.3158994.1462816081729.JavaMail.zimbra@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi, Looks good to me. ACK. Cheers! --Abhi ----- Original Message ----- > From: "Bob Peterson" > To: "cluster-devel" > Sent: Friday, May 6, 2016 12:38:53 PM > Subject: [Cluster-devel] [fsck.gfs2 v2 PATCH 00/40] fsck.gfs2: memory reduction patches > > On 15 April, I posted a set of 30 patches for fsck.gfs2 to reduce its > memory requirements. Since that time, I've been testing and fixing > problems. Here is version 2. > --- > Right now, fsck.gfs2 is a memory hog with regard to very large file > systems. A file system of 250TB would require an absurd about of memory. > That's because it uses memory for (1) rgrp bitmaps, (2) its own internal > blockmap, (3) a directory tree, and (4) a tree of ALL inodes in the > file system, for reconciling link counts. > > This series of 40 patches is designed to reduce the memory footprint > of fsck.gfs2. It does so by almost entirely eliminating the inode > tree in favor of two much smaller bitmaps. In order to do that, I > rearranged the order in which things are done. > > In order to save on memory, some things will be slower, so this will > cause a performance hit to fsck.gfs2. However, I'm confident that > we can fix them and make it fast again. The slowness is caused because > most bitmap manipulation is now done on the bitmaps in the resource > groups, which means the code needs to search out the rgrp for these > operations. This can be optimized to pass in the rgrp, since it will > be known in most cases (for example, pass1 operates on one rgrp at a > time, and chances are quite good that the rgrp needed will be that one.) > These further optimizations will be done in later patches. > > I'm still testing these changes against my collection of gfs2 and gfs1 > metadata, but the results are good so far. So there may be changes. > > Signed-off-by: Bob Peterson