Hello! You've got a good idea too. Thanks! 2007/6/8, devsk <funtoos@xxxxxxxxx>:
> you may use "#mount /dev/sda1 /mnt/tmp -o fsync=10" which means "fsync > once when invoked fsync 10 times" or if 5 (may be use sys.vm.dirty_writeback_centisecs) seconds have elapsed since last fsync. -devsk ----- Original Message ---- From: Xu CanHao <xucanhao@xxxxxxxxx> To: reiserfs-devel@xxxxxxxxxxxxxxx Sent: Thursday, June 7, 2007 5:14:46 AM Subject: Reiser4 performance bottlenecks and possible solutions Hello! Since performance is one of the most important aspect of Reiser4, I indeed encountered some performance bottlenecks of Reiser4 during my daily usage. The following is my own(possibly wrong) experiences: 1, Tail-conversion/Extent-only May save space at a 5-10 percent, while impacts performance much more greater. Extent-only performs better. 2, read()... Old read_unix_file() is not efficient, especially in read_unix_file_container_tails(). So I think generic_file_read() is better for Extent-only users. 1+2, Extent-only + generic_file_read() During my benchmark, 1+2 provides 10%-400% better performance(varies with the benchmark utility) 3, fsync() Terrible fsync() performance has been talked for a thousand times without a full solution. I'm thinking of a temporary solution: adding a mount option and let the user determine the fsync() frequency(yes, you may lose data when power-fail), things like: int sync_unix_file(struct file *file, struct dentry *dentry, int datasync) { reiser4_context *ctx; txn_atom *atom; reiser4_block_nr reserve; reiser4_super_info_data *sbinfo; ctx = init_context(dentry->d_inode->i_sb); if (IS_ERR(ctx)) return PTR_ERR(ctx); sbinfo = get_current_super_private(); if (sbinfo->fsync == 0) { reiser4_exit_context(ctx); return 0; } else if (sbinfo->fsync == 1) { fsync_file: reserve = estimate_update_common(dentry->d_inode); if (reiser4_grab_space(reserve, BA_CAN_COMMIT)) { reiser4_exit_context(ctx); return RETERR(-ENOSPC); } write_sd_by_inode_common(dentry->d_inode); atom = get_current_atom_locked(); spin_lock_txnh(ctx->trans); force_commit_atom(ctx->trans); reiser4_exit_context(ctx); return 0; } else if (sbinfo->fsync > 1) { fsync_num++; if (fsync_num >= sbinfo->fsync) { fsync_num = 0; goto fsync_file; } reiser4_exit_context(ctx); return 0; } return 0; } you may use "#mount /dev/sda1 /mnt/tmp -o fsync=10" which means "fsync once when invoked fsync 10 times" 4, Relocation/Overwrite Should you take 1+2 the default value 64 of flush.relocate_threshold and flush.relocate_distance may not suitable, a lower value maybe better for most case. 1+2+3+4 If you take all of them, the performance gain would be dramatically and still as stable as before, at least for my months of experience. Thanks! - To unsubscribe from this list: send the line "unsubscribe reiserfs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html ________________________________ Sucker-punch spam with award-winning protection. Try the free Yahoo! Mail Beta.
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