On Thu, May 27, 2021 at 02:52:02PM +1000, Dave Chinner wrote: > From: Dave Chinner <dchinner@xxxxxxxxxx> > > Ever since we moved to deferred freeing of extents, we only every > free one extent per transaction. We separated the bulk unmapping of > extents from the submission of EFI/free/EFD transactions, and hence > while we unmap extents in bulk, we only every free one per > transaction. > > Our transaction reservations still live in the era from before > deferred freeing of extents, so still refer to "xfs_bmap_finish" > and it needing to free multiple extents per transaction. These > freeing reservations can now all be reduced to a single extent to > reflect how we currently free extents. > > This significantly reduces the reservation sizes for operations like > truncate and directory operations where they currently reserve space > for freeing up to 4 extents per transaction. > > For a 4kB block size filesytsem with reflink=1,rmapbt=1, the > reservation sizes change like this: > > Reservation Before After > (index) logres logcount logres logcount > 0 write 314104 8 314104 8 > 1 itruncate 579456 8 148608 8 > 2 rename 435840 2 307936 2 > 3 link 191600 2 191600 2 > 4 remove 312960 2 174328 2 > 5 symlink 470656 3 470656 3 > 6 create 469504 2 469504 2 > 7 create_tmpfile 490240 2 490240 2 > 8 mkdir 469504 3 469504 3 > 9 ifree 508664 2 508664 2 > 10 ichange 5752 0 5752 0 > 11 growdata 147840 2 147840 2 > 12 addafork 178936 2 178936 2 > 13 writeid 760 0 760 0 > 14 attrinval 578688 1 147840 1 > 15 attrsetm 26872 3 26872 3 > 16 attrsetrt 16896 0 16896 0 > 17 attrrm 292224 3 148608 3 > 18 clearagi 4224 0 4224 0 > 19 growrtalloc 173944 2 173944 2 > 20 growrtzero 4224 0 4224 0 > 21 growrtfree 10096 0 10096 0 > 22 qm_setqlim 232 1 232 1 > 23 qm_dqalloc 318327 8 318327 8 > 24 qm_quotaoff 4544 1 4544 1 > 25 qm_equotaoff 320 1 320 1 > 26 sb 4224 1 4224 1 > 27 fsyncts 760 0 760 0 > MAX 579456 8 318327 8 > > So we can see that many of the reservations have gone substantially > down in size. itruncate, rename, remove, attrinval and attrrm are > much smaller now. The maximum reservation size has gone from being > attrinval at 579456*8 bytes to dqalloc at 318327*8 bytes. This is a > substantial improvement for common operations. If you're going to play around with log reservations, can you have a quick look at the branch I made to fix all the oversized reservations that we make for rmap and reflink? https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git/log/?h=reflink-speedups That's what's next after deferred inode inactivation lands. --D > > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> > --- > fs/xfs/libxfs/xfs_trans_resv.c | 63 +++++++++++++++++----------------- > 1 file changed, 31 insertions(+), 32 deletions(-) > > diff --git a/fs/xfs/libxfs/xfs_trans_resv.c b/fs/xfs/libxfs/xfs_trans_resv.c > index 02079f55ef20..f5e76eeae281 100644 > --- a/fs/xfs/libxfs/xfs_trans_resv.c > +++ b/fs/xfs/libxfs/xfs_trans_resv.c > @@ -232,8 +232,7 @@ xfs_rtalloc_log_count( > * Various log reservation values. > * > * These are based on the size of the file system block because that is what > - * most transactions manipulate. Each adds in an additional 128 bytes per > - * item logged to try to account for the overhead of the transaction mechanism. > + * most transactions manipulate. > * > * Note: Most of the reservations underestimate the number of allocation > * groups into which they could free extents in the xfs_defer_finish() call. > @@ -262,9 +261,9 @@ xfs_rtalloc_log_count( > * the superblock free block counter: sector size > * the realtime bitmap: ((MAXEXTLEN / rtextsize) / NBBY) bytes > * the realtime summary: 1 block > - * And the bmap_finish transaction can free bmap blocks in a join (t3): > + * And the deferred freeing can free bmap blocks in a join (t3): > * the super block free block counter: sector size > - * two extent allocfree reservations for the AG. > + * one extent allocfree reservation for the AG. > */ > STATIC uint > xfs_calc_write_reservation( > @@ -290,23 +289,25 @@ xfs_calc_write_reservation( > } > > t3 = xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) + > - xfs_allocfree_extent_res(mp) * 2; > + xfs_allocfree_extent_res(mp); > > return XFS_DQUOT_LOGRES(mp) + max3(t1, t2, t3); > } > > /* > - * In truncating a file we free up to two extents at once. We can modify (t1): > + * In truncating a file we defer freeing so we only free one extent per > + * transaction for normal files. For rt files we limit to 2 extents per > + * transaction. > + * We can modify (t1): > * the inode being truncated: inode size > * the inode's bmap btree: (max depth + 1) * block size > - * And the bmap_finish transaction can free the blocks and bmap blocks (t2): > - * the super block to reflect the freed blocks: sector size > - * four extent allocfree reservations for the AG. > - * Or, if it's a realtime file (t3): > + * Or, if it's a realtime file (t2): > * the super block to reflect the freed blocks: sector size > * the realtime bitmap: 2 exts * ((MAXEXTLEN / rtextsize) / NBBY) bytes > * the realtime summary: 2 exts * 1 block > - * two extent allocfree reservations for the AG. > + * And the deferred freeing can free the blocks and bmap blocks (t3): > + * the super block to reflect the freed blocks: sector size > + * one extent allocfree reservation for the AG. > */ > STATIC uint > xfs_calc_itruncate_reservation( > @@ -318,17 +319,16 @@ xfs_calc_itruncate_reservation( > t1 = xfs_calc_inode_res(mp, 1) + > xfs_calc_buf_res(XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK) + 1, blksz); > > - t2 = xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) + > - xfs_allocfree_extent_res(mp) * 4; > - > if (xfs_sb_version_hasrealtime(&mp->m_sb)) { > - t3 = xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) + > - xfs_calc_buf_res(xfs_rtalloc_log_count(mp, 2), blksz) + > - xfs_allocfree_extent_res(mp) * 2; > + t2 = xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) + > + xfs_calc_buf_res(xfs_rtalloc_log_count(mp, 2), blksz); > } else { > - t3 = 0; > + t2 = 0; > } > > + t3 = xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) + > + xfs_allocfree_extent_res(mp); > + > return XFS_DQUOT_LOGRES(mp) + max3(t1, t2, t3); > } > > @@ -337,10 +337,9 @@ xfs_calc_itruncate_reservation( > * the four inodes involved: 4 * inode size > * the two directory btrees: 2 * (max depth + v2) * dir block size > * the two directory bmap btrees: 2 * max depth * block size > - * And the bmap_finish transaction can free dir and bmap blocks (two sets > - * of bmap blocks) giving: > + * And the deferred freeing can free dir and bmap blocks giving: > * the superblock for the free block count: sector size > - * three extent allocfree reservations for the AG. > + * one extent allocfree reservations for the AG. > */ > STATIC uint > xfs_calc_rename_reservation( > @@ -351,7 +350,7 @@ xfs_calc_rename_reservation( > xfs_calc_buf_res(2 * XFS_DIROP_LOG_COUNT(mp), > XFS_FSB_TO_B(mp, 1))), > (xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) + > - xfs_allocfree_extent_res(mp) * 3)); > + xfs_allocfree_extent_res(mp))); > } > > /* > @@ -375,7 +374,7 @@ xfs_calc_iunlink_remove_reservation( > * the linked inode: inode size > * the directory btree could split: (max depth + v2) * dir block size > * the directory bmap btree could join or split: (max depth + v2) * blocksize > - * And the bmap_finish transaction can free some bmap blocks giving: > + * And the deferred freeing can free bmap blocks giving: > * the superblock for the free block count: sector size > * one extent allocfree reservation for the AG. > */ > @@ -411,9 +410,9 @@ xfs_calc_iunlink_add_reservation(xfs_mount_t *mp) > * the removed inode: inode size > * the directory btree could join: (max depth + v2) * dir block size > * the directory bmap btree could join or split: (max depth + v2) * blocksize > - * And the bmap_finish transaction can free the dir and bmap blocks giving: > + * And the deferred freeing can free the dir and bmap blocks giving: > * the superblock for the free block count: sector size > - * two extent allocfree reservations for the AG. > + * one extent allocfree reservation for the AG. > */ > STATIC uint > xfs_calc_remove_reservation( > @@ -425,7 +424,7 @@ xfs_calc_remove_reservation( > xfs_calc_buf_res(XFS_DIROP_LOG_COUNT(mp), > XFS_FSB_TO_B(mp, 1))), > (xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) + > - xfs_allocfree_extent_res(mp) * 2)); > + xfs_allocfree_extent_res(mp))); > } > > /* > @@ -670,9 +669,9 @@ xfs_calc_addafork_reservation( > * Removing the attribute fork of a file > * the inode being truncated: inode size > * the inode's bmap btree: max depth * block size > - * And the bmap_finish transaction can free the blocks and bmap blocks: > + * And the deferred freeing can free the blocks and bmap blocks: > * the super block to reflect the freed blocks: sector size > - * four extent allocfree reservations for the AG. > + * one extent allocfree reservation for the AG. > */ > STATIC uint > xfs_calc_attrinval_reservation( > @@ -682,7 +681,7 @@ xfs_calc_attrinval_reservation( > xfs_calc_buf_res(XFS_BM_MAXLEVELS(mp, XFS_ATTR_FORK), > XFS_FSB_TO_B(mp, 1))), > (xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) + > - xfs_allocfree_extent_res(mp) * 4)); > + xfs_allocfree_extent_res(mp))); > } > > /* > @@ -730,9 +729,9 @@ xfs_calc_attrsetrt_reservation( > * the inode: inode size > * the attribute btree could join: max depth * block size > * the inode bmap btree could join or split: max depth * block size > - * And the bmap_finish transaction can free the attr blocks freed giving: > + * And the deferred freeing can free the attr blocks freed giving: > * the superblock for the free block count: sector size > - * two extent allocfree reservations for the AG. > + * one extent allocfree reservations for the AG. > */ > STATIC uint > xfs_calc_attrrm_reservation( > @@ -746,7 +745,7 @@ xfs_calc_attrrm_reservation( > XFS_BM_MAXLEVELS(mp, XFS_ATTR_FORK)) + > xfs_calc_buf_res(XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK), 0)), > (xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) + > - xfs_allocfree_extent_res(mp) * 2)); > + xfs_allocfree_extent_res(mp))); > } > > /* > -- > 2.31.1 >
