| Message ID | 20160107004639.GA3902@server_lokesh.domain.name |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Jan 6, 2016, at 5:46 PM, Lokesh Jaliminche <lokesh.jaliminche@gmail.com> wrote: > > you are right flex groups cannot be completely empty as some > blocks are used for inode table and allocation bitmaps. I > missed that point. I have corrected that. Also I have tested > and validated this patch by putting some traces it works! Good news. Thanks for updating the patch and testing it. More comments below. > Here are corresponding logs: > commands: > ========= > mkfs.ext4 -g 10000 -G 2 /dev/sdc > mount -t ext4 /dev/sdc /mnt/test_ext4/ > cd /mnt/test_ext4 > mkdir 1 > cd 1 > > logs: > ===== > Jan 7 03:36:45 root kernel: [ 64.792939] max_usable_blocks_per_flex_group = [19692] > Jan 7 03:36:45 root kernel: [ 64.792939] stats.free_clusters = [19264] > Jan 7 03:36:45 root kernel: [ 64.792939] Inodes_per_flex_group = [4864] > Jan 7 03:36:45 root kernel: [ 64.792939] stats.free_inodes = [4853] > Jan 7 03:36:45 root kernel: [ 64.792950] max_usable_blocks_per_flex_group = [19692] > Jan 7 03:36:45 root kernel: [ 64.792950] stats.free_clusters = [19481] > Jan 7 03:36:45 root kernel: [ 64.792950] Inodes_per_flex_group = [4864] > Jan 7 03:36:45 root kernel: [ 64.792950] stats.free_inodes = [4864] > Jan 7 03:36:45 root kernel: [ 64.792958] max_usable_blocks_per_flex_group = [19692] > Jan 7 03:36:45 root kernel: [ 64.792958] stats.free_clusters = [19481] > Jan 7 03:36:45 root kernel: [ 64.792958] Inodes_per_flex_group = [4864] > Jan 7 03:36:45 root kernel: [ 64.792958] stats.free_inodes = [4864] > Jan 7 03:36:45 root kernel: [ 64.792965] max_usable_blocks_per_flex_group = [19692] > Jan 7 03:36:45 root kernel: [ 64.792965] stats.free_clusters = [19481] > Jan 7 03:36:45 root kernel: [ 64.792965] Inodes_per_flex_group = [4864] > Jan 7 03:36:45 root kernel: [ 64.792965] stats.free_inodes = [4864] > Jan 7 03:36:45 root kernel: [ 64.792972] max_usable_blocks_per_flex_group = [19692] > Jan 7 03:36:45 root kernel: [ 64.792972] stats.free_clusters = [19481] > Jan 7 03:36:45 root kernel: [ 64.792972] Inodes_per_flex_group = [4864] > Jan 7 03:36:45 root kernel: [ 64.792972] stats.free_inodes = [4864] > Jan 7 03:36:45 root kernel: [ 64.792979] max_usable_blocks_per_flex_group = [19692]<<<<<<<<<<< > Jan 7 03:36:45 root kernel: [ 64.792979] stats.free_clusters = [19692]<<<<<<<<<<< > Jan 7 03:36:45 root kernel: [ 64.792979] Inodes_per_flex_group = [4864]<<<<<<<<<<<< > Jan 7 03:36:45 root kernel: [ 64.792979] stats.free_inodes = [4864]<<<<<<<<<<<< > Jan 7 03:36:45 root kernel: [ 64.792985] found_flex_bg >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>condition satisfied > > > [Patch v4]: > ========== > From: Lokesh Nagappa Jaliminche <lokesh.jaliminche@gmail.com> > Date: Thu, 7 Jan 2016 05:12:20 +0530 > Subject: [PATCH] ext4: optimizing group serch for inode allocation > > Added a check at the start of group search loop to > avoid looping unecessarily in case of empty group. > This also allow group search to jump directly to > "found_flex_bg" with "stats" and "group" already set, > so there is no need to go through the extra steps of > setting "best_desc" , "best_group" and then break > out of the loop just to set "stats" and "group" again. > > Signed-off-by: Lokesh Nagappa Jaliminche <lokesh.jaliminche@gmail.com> > --- > fs/ext4/ext4.h | 2 ++ > fs/ext4/ialloc.c | 21 +++++++++++++++++++-- > 2 files changed, 21 insertions(+), 2 deletions(-) > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h > index cc7ca4e..fc48f9a 100644 > --- a/fs/ext4/ext4.h > +++ b/fs/ext4/ext4.h > @@ -326,6 +326,8 @@ struct flex_groups { > #define EXT4_MAX_DESC_SIZE EXT4_MIN_BLOCK_SIZE > #define EXT4_DESC_SIZE(s) (EXT4_SB(s)->s_desc_size) > #ifdef __KERNEL__ > +# define EXT4_INODE_TABLE_BLOCKS_PER_GROUP(s) (EXT4_SB(s)->s_itb_per_group) > +# define EXT4_BLOCKS_PER_CLUSTER(s) (EXT4_SB(s)->s_cluster_ratio) I don't think there is much value to these macros. They aren't much shorter than the actual variable access, and they don't provide any improved clarity for the reader. I think they were introduced many years ago so that this header could be shared between the kernel and e2fsprogs, but that is no longer true so I don't think there is a need to add new ones. Ted, any opinion on this? > # define EXT4_BLOCKS_PER_GROUP(s) (EXT4_SB(s)->s_blocks_per_group) > # define EXT4_CLUSTERS_PER_GROUP(s) (EXT4_SB(s)->s_clusters_per_group) > # define EXT4_DESC_PER_BLOCK(s) (EXT4_SB(s)->s_desc_per_block) > diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c > index 1b8024d..dc66ad8 100644 > --- a/fs/ext4/ialloc.c > +++ b/fs/ext4/ialloc.c > @@ -463,7 +463,6 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, > sbi->s_log_groups_per_flex; > parent_group >>= sbi->s_log_groups_per_flex; > } > - > freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter); > avefreei = freei / ngroups; Not sure why this line is being deleted? > @@ -477,7 +476,20 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, > (ext4_test_inode_flag(parent, EXT4_INODE_TOPDIR)))) { > int best_ndir = inodes_per_group; > int ret = -1; > - > + /* blocks used for inode table and allocation bitmaps */ > + unsigned int max_usable_blocks_per_flex_group; This could be shorter and still clear, like "max_blocks_per_flex". > + unsigned int blocks_per_group = EXT4_BLOCKS_PER_GROUP(sb); > + unsigned int inode_table_blocks_per_group = \ > + EXT4_INODE_TABLE_BLOCKS_PER_GROUP(sb); > + /* Number of blocks per cluster */ > + unsigned int cluster_ratio = EXT4_BLOCKS_PER_CLUSTER(sb); There also isn't much value to making local variables that hold these same values again. It increases stack space for little benefit. They are only accessed once anyway. > + unsigned int inodes_per_flex_group = inodes_per_group * \ > + flex_size; > + max_usable_blocks_per_flex_group = \ > + ((blocks_per_group*flex_size) - \ Spaces around that '*'. > + (inode_table_blocks_per_group * \ > + flex_size + 2 * flex_size)) / \ This is C and not a CPP macro, so no need for linefeed escapes. > + cluster_ratio; This should be ">> EXT4_SB(sb)->s_cluster_bits" to avoid the divide. > if (qstr) { > hinfo.hash_version = DX_HASH_HALF_MD4; > hinfo.seed = sbi->s_hash_seed; > @@ -489,6 +501,11 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, > for (i = 0; i < ngroups; i++) { > g = (parent_group + i) % ngroups; > get_orlov_stats(sb, g, flex_size, &stats); > + /* can't get better group than empty group */ > + if (max_usable_blocks_per_flex_group == \ > + stats.free_clusters && \ No need for linefeed escapes. > + inodes_per_flex_group == stats.free_inodes) Align continued line after '(' from the "if (" line. > + goto found_flex_bg; This is indented too much. It will work properly when you fix the previous line. > if (!stats.free_inodes) > continue; > if (stats.used_dirs >= best_ndir) > -- > 1.7.1 > > Regards, > Lokesh > > On Sun, Jan 03, 2016 at 11:34:51AM -0700, Andreas Dilger wrote: >> On Dec 26, 2015, at 01:41, Lokesh Jaliminche <lokesh.jaliminche@gmail.com> wrote: >>> >>> >>> From 5199982d29ff291b181c25af63a22d6f2d6d3f7b Mon Sep 17 00:00:00 2001 >>> From: Lokesh Nagappa Jaliminche <lokesh.jaliminche@gmail.com> >>> Date: Sat, 26 Dec 2015 13:19:36 +0530 >>> Subject: [PATCH v3] ext4: optimizing group search for inode allocation >>> >>> Added a check at the start of group search loop to >>> avoid looping unecessarily in case of empty group. >>> This also allow group search to jump directly to >>> "found_flex_bg" with "stats" and "group" already set, >>> so there is no need to go through the extra steps of >>> setting "best_desc" and "best_group" and then break >>> out of the loop just to set "stats" and "group" again. >>> >>> Signed-off-by: Lokesh Nagappa Jaliminche <lokesh.jaliminche@gmail.com> >>> --- >>> fs/ext4/ialloc.c | 12 ++++++++++-- >>> 1 files changed, 10 insertions(+), 2 deletions(-) >>> >>> diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c >>> index 1b8024d..16f94db 100644 >>> --- a/fs/ext4/ialloc.c >>> +++ b/fs/ext4/ialloc.c >>> @@ -473,10 +473,14 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, >>> ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter); >>> >>> if (S_ISDIR(mode) && >>> - ((parent == d_inode(sb->s_root)) || >>> - (ext4_test_inode_flag(parent, EXT4_INODE_TOPDIR)))) { >>> + ((parent == d_inode(sb->s_root)) || >>> + (ext4_test_inode_flag(parent, EXT4_INODE_TOPDIR)))) { >> >> I don't understand why you are changing the indentation here? >> >>> + unsigned int inodes_per_flex_group; >>> + unsigned long int clusters_per_flex_group; >>> int best_ndir = inodes_per_group; >>> int ret = -1; >>> + inodes_per_flex_group = inodes_per_group * flex_size; >>> + clusters_per_flex_group = sbi->s_clusters_per_group * flex_size; >> >> Have you actually tested if this code works? When I was looking at this >> code I was accidentally looking at the ext2 version, which only deals with >> individual groups, and not flex groups. I don't think that a flex group >> can actually be completely empty, since it will always contain at least >> an inode table and some bitmaps. >> >> This calculation needs to take this into account or it will just be >> overhead and not an optimization. Something like: >> >> /* account for inode table and allocation bitmaps */ >> clusters_per_flex_group = sbi->s_clusters_per_group * flex_size - >> ((inodes_per_flex_group * EXT4_INODE_SIZE(sb) + >> (flex_size << sb->s_blocksize_bits) * 2 ) >> >> EXT4_SB(sb)->s_cluster_bits; >> >> It would be worthwhile to print this out and verify that there are actually >> groups with this many free blocks in a newly formatted filesystem. >> >> Cheers, Andreas >> >>> if (qstr) { >>> hinfo.hash_version = DX_HASH_HALF_MD4; >>> @@ -489,6 +493,10 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, >>> for (i = 0; i < ngroups; i++) { >>> g = (parent_group + i) % ngroups; >>> get_orlov_stats(sb, g, flex_size, &stats); >>> + /* the group can't get any better than empty */ >>> + if (inodes_per_flex_group == stats.free_inodes && >>> + clusters_per_flex_group == stats.free_clusters) >>> + goto found_flex_bg; >>> if (!stats.free_inodes) >>> continue; >>> if (stats.used_dirs >= best_ndir) >>> -- >>> 1.7.1 >>> >>> >>>> On Mon, Dec 21, 2015 at 10:27:37AM -0700, Andreas Dilger wrote: >>>>> On Dec 18, 2015, at 4:32 PM, lokesh jaliminche <lokesh.jaliminche@gmail.com> wrote: >>>>> >>>>> From 9e09fef78b2fa552c883bf8124af873abfde0805 Mon Sep 17 00:00:00 2001 >>>>> From: Lokesh Nagappa Jaliminche <lokesh.jaliminche@seagate.com> >>>> >>>> In the patch summary there is a typo - s/serch/search/ >>>> >>>> Also, it appears your email client has mangled the whitespace in the >>>> patch. Please use "git send-email" to send your patch to the list: >>>> >>>> git send-email --to tytso@mit.edu --cc linux-ext4@vger.kernel.org HEAD~1 >>>> >>>> so that it arrives intact. You probably need to set it up in ~/.gitconfig: >>>> >>>> [sendemail] >>>> confirm = compose >>>> smtpdomain = {your client hostname} >>>> smtpserver = {your SMTP server hostname} >>>> >>>> Cheers, Andreas >>>> >>>>> Added a check at the start of group search loop to >>>>> avoid looping unecessarily in case of empty group. >>>>> This also allow group search to jump directly to >>>>> "found_flex_bg" with "stats" and "group" already set, >>>>> so there is no need to go through the extra steps of >>>>> setting "best_desc" and "best_group" and then break >>>>> out of the loop just to set "stats" and "group" again. >>>>> >>>>> Signed-off-by: Lokesh N Jaliminche <lokesh.jaliminche@gmail.com> >>>>> --- >>>>> fs/ext4/ialloc.c | 8 ++++++++ >>>>> 1 files changed, 8 insertions(+), 0 deletions(-) >>>>> >>>>> diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c >>>>> index 1b8024d..588bf8e 100644 >>>>> --- a/fs/ext4/ialloc.c >>>>> +++ b/fs/ext4/ialloc.c >>>>> @@ -446,6 +446,8 @@ static int find_group_orlov(struct super_block >>>>> *sb, struct inode *parent, >>>>> struct ext4_sb_info *sbi = EXT4_SB(sb); >>>>> ext4_group_t real_ngroups = ext4_get_groups_count(sb); >>>>> int inodes_per_group = EXT4_INODES_PER_GROUP(sb); >>>>> + unsigned int inodes_per_flex_group; >>>>> + long unsigned int blocks_per_clustre; >>>>> unsigned int freei, avefreei, grp_free; >>>>> ext4_fsblk_t freeb, avefreec; >>>>> unsigned int ndirs; >>>>> @@ -470,6 +472,8 @@ static int find_group_orlov(struct super_block >>>>> *sb, struct inode *parent, >>>>> percpu_counter_read_positive(&sbi->s_freeclusters_counter)); >>>>> avefreec = freeb; >>>>> do_div(avefreec, ngroups); >>>>> + inodes_per_flex_group = inodes_per_group * flex_size; >>>>> + blocks_per_clustre = sbi->s_blocks_per_group * flex_size; >>>>> ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter); >>>>> >>>>> if (S_ISDIR(mode) && >>>>> @@ -489,6 +493,10 @@ static int find_group_orlov(struct super_block >>>>> *sb, struct inode *parent, >>>>> for (i = 0; i < ngroups; i++) { >>>>> g = (parent_group + i) % ngroups; >>>>> get_orlov_stats(sb, g, flex_size, &stats); >>>>> + /* the group can't get any better than empty */ >>>>> + if (inodes_per_flex_group == stats.free_inodes && >>>>> + blocks_per_clustre == stats.free_clusters) >>>>> + goto found_flex_bg; >>>>> if (!stats.free_inodes) >>>>> continue; >>>>> if (stats.used_dirs >= best_ndir) >>>>> -- >>>>> 1.7.1 >>>>> <0001-EXT4-optimizing-group-serch-for-inode-allocation.patch> >>>> >>>> >>>> Cheers, Andreas >>> >>> >>> <0001-ext4-optimizing-group-serch-for-inode-allocation.patch> > <0001-ext4-optimizing-group-serch-for-inode-allocation.patch> Cheers, Andreas
========= mkfs.ext4 -g 10000 -G 2 /dev/sdc mount -t ext4 /dev/sdc /mnt/test_ext4/ cd /mnt/test_ext4 mkdir 1 cd 1 logs: ===== Jan 7 03:36:45 root kernel: [ 64.792939] max_usable_blocks_per_flex_group = [19692] Jan 7 03:36:45 root kernel: [ 64.792939] stats.free_clusters = [19264] Jan 7 03:36:45 root kernel: [ 64.792939] Inodes_per_flex_group = [4864] Jan 7 03:36:45 root kernel: [ 64.792939] stats.free_inodes = [4853] Jan 7 03:36:45 root kernel: [ 64.792950] max_usable_blocks_per_flex_group = [19692] Jan 7 03:36:45 root kernel: [ 64.792950] stats.free_clusters = [19481] Jan 7 03:36:45 root kernel: [ 64.792950] Inodes_per_flex_group = [4864] Jan 7 03:36:45 root kernel: [ 64.792950] stats.free_inodes = [4864] Jan 7 03:36:45 root kernel: [ 64.792958] max_usable_blocks_per_flex_group = [19692] Jan 7 03:36:45 root kernel: [ 64.792958] stats.free_clusters = [19481] Jan 7 03:36:45 root kernel: [ 64.792958] Inodes_per_flex_group = [4864] Jan 7 03:36:45 root kernel: [ 64.792958] stats.free_inodes = [4864] Jan 7 03:36:45 root kernel: [ 64.792965] max_usable_blocks_per_flex_group = [19692] Jan 7 03:36:45 root kernel: [ 64.792965] stats.free_clusters = [19481] Jan 7 03:36:45 root kernel: [ 64.792965] Inodes_per_flex_group = [4864] Jan 7 03:36:45 root kernel: [ 64.792965] stats.free_inodes = [4864] Jan 7 03:36:45 root kernel: [ 64.792972] max_usable_blocks_per_flex_group = [19692] Jan 7 03:36:45 root kernel: [ 64.792972] stats.free_clusters = [19481] Jan 7 03:36:45 root kernel: [ 64.792972] Inodes_per_flex_group = [4864] Jan 7 03:36:45 root kernel: [ 64.792972] stats.free_inodes = [4864] Jan 7 03:36:45 root kernel: [ 64.792979] max_usable_blocks_per_flex_group = [19692]<<<<<<<<<<< Jan 7 03:36:45 root kernel: [ 64.792979] stats.free_clusters = [19692]<<<<<<<<<<< Jan 7 03:36:45 root kernel: [ 64.792979] Inodes_per_flex_group = [4864]<<<<<<<<<<<< Jan 7 03:36:45 root kernel: [ 64.792979] stats.free_inodes = [4864]<<<<<<<<<<<< Jan 7 03:36:45 root kernel: [ 64.792985] found_flex_bg >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>condition satisfied [Patch v4]: ========== From: Lokesh Nagappa Jaliminche <lokesh.jaliminche@gmail.com> Date: Thu, 7 Jan 2016 05:12:20 +0530 Subject: [PATCH] ext4: optimizing group serch for inode allocation Added a check at the start of group search loop to avoid looping unecessarily in case of empty group. This also allow group search to jump directly to "found_flex_bg" with "stats" and "group" already set, so there is no need to go through the extra steps of setting "best_desc" , "best_group" and then break out of the loop just to set "stats" and "group" again. Signed-off-by: Lokesh Nagappa Jaliminche <lokesh.jaliminche@gmail.com> --- fs/ext4/ext4.h | 2 ++ fs/ext4/ialloc.c | 21 +++++++++++++++++++-- 2 files changed, 21 insertions(+), 2 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index cc7ca4e..fc48f9a 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -326,6 +326,8 @@ struct flex_groups { #define EXT4_MAX_DESC_SIZE EXT4_MIN_BLOCK_SIZE #define EXT4_DESC_SIZE(s) (EXT4_SB(s)->s_desc_size) #ifdef __KERNEL__ +# define EXT4_INODE_TABLE_BLOCKS_PER_GROUP(s) (EXT4_SB(s)->s_itb_per_group) +# define EXT4_BLOCKS_PER_CLUSTER(s) (EXT4_SB(s)->s_cluster_ratio) # define EXT4_BLOCKS_PER_GROUP(s) (EXT4_SB(s)->s_blocks_per_group) # define EXT4_CLUSTERS_PER_GROUP(s) (EXT4_SB(s)->s_clusters_per_group) # define EXT4_DESC_PER_BLOCK(s) (EXT4_SB(s)->s_desc_per_block) diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index 1b8024d..dc66ad8 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -463,7 +463,6 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, sbi->s_log_groups_per_flex; parent_group >>= sbi->s_log_groups_per_flex; } - freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter); avefreei = freei / ngroups; freeb = EXT4_C2B(sbi, @@ -477,7 +476,20 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, (ext4_test_inode_flag(parent, EXT4_INODE_TOPDIR)))) { int best_ndir = inodes_per_group; int ret = -1; - + /* blocks used for inode table and allocation bitmaps */ + unsigned int max_usable_blocks_per_flex_group; + unsigned int blocks_per_group = EXT4_BLOCKS_PER_GROUP(sb); + unsigned int inode_table_blocks_per_group = \ + EXT4_INODE_TABLE_BLOCKS_PER_GROUP(sb); + /* Number of blocks per cluster */ + unsigned int cluster_ratio = EXT4_BLOCKS_PER_CLUSTER(sb); + unsigned int inodes_per_flex_group = inodes_per_group * \ + flex_size; + max_usable_blocks_per_flex_group = \ + ((blocks_per_group*flex_size) - \ + (inode_table_blocks_per_group * \ + flex_size + 2 * flex_size)) / \ + cluster_ratio; if (qstr) { hinfo.hash_version = DX_HASH_HALF_MD4; hinfo.seed = sbi->s_hash_seed; @@ -489,6 +501,11 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, for (i = 0; i < ngroups; i++) { g = (parent_group + i) % ngroups; get_orlov_stats(sb, g, flex_size, &stats); + /* can't get better group than empty group */ + if (max_usable_blocks_per_flex_group == \ + stats.free_clusters && \ + inodes_per_flex_group == stats.free_inodes) + goto found_flex_bg; if (!stats.free_inodes) continue; if (stats.used_dirs >= best_ndir)