如图,journal_async_commit虽然能够提高性能,由于journal_async_commit打开的同时也必须打开journal_checksum,我们另外测试了两组来衡量journal_checksum对性能的影响(这两组默认没有打开journal_async_commit)只测journal_checksum,从我们的测试结果来看,journal_checksum对性能影响不大,
1、journal_checksum 使能checksumming。允许回复代码和内核对内核的变体进行监测,其为向后兼容,并且会被较老版本的内核忽略。 2、journal_async_commit 提交块无需等待描述符块即可写入磁盘。 3、barrier=0 / barrier=1 / barrier / nobarrier have the same effect as in ext3.装载选项“barrier”和“nobarrier...
if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_ORDERED_DATA && test_opt(sb, JOURNAL_ASYNC_COMMIT)) { ext4_msg(sb, KERN_ERR, "can't mount with journal_async_commit " "in data=ordered mode"); return 0; } return 1; } 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14...
* (they were dirtied by commit). But that's OK - the blocks are * safe in-journal, which is all fsync() needs to ensure. */ if (ext4_should_journal_data(inode)) return ext4_force_commit(inode->i_sb); commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; if (j...
For those with concerns about both data integrity and performance, the journaling can be significantly sped up with the journal_async_commit mount option. Note that it does not work with the balanced default of data=ordered, so this is only recommended when the filesystem is already cautiously ...
都在等待 Transaction Commit 的完成。jbd2_log_wait_commit() 正在j_wait_done_commit队列中等待唤醒,只有当类别1的Journal线程完成 jbd2_journal_commit_transaction() 时,才会调用wake_up(&journal->j_wait_done_commit)唤醒该类进程,因此阻塞等待在这个栈的线程正在等待类别1的Journal 线程。
数据写入磁盘时理应先写入journal区,再写入数据在磁盘的实际对应位置。磁盘厂商为了加快磁盘写入速度磁盘都内置cache,数据一般都先写入磁盘的cache.。cache能加快写入速度,当然是极好的东西,但磁盘一般会对cache内缓存数据排序使之最优刷新到磁盘,这样就可能导致要刷新的实际数据和journal顺序错乱。一旦系统崩溃,下次开机时...
874 - static int ext4_dio_get_block_unwritten_async(struct inode *inode, 875 - sector_t iblock, struct buffer_head *bh_result, int create) 876 - { 877 - int ret; 878 - 879 - /* We don't expect handle for direct IO */ 880 - WARN_ON_ONCE(ext4_journal_current_handle...
contemporary drives maintain large internal caches and will reorder operations for better performance. So the filesystem must explicitly instruct the disk to get all of the journal data onto the media before writing the commit record; if the commit record gets written first, the journal may be co...
Opt_commit, Opt_min_batch_time, Opt_max_batch_time, Opt_journal_dev, Opt_journal_path, Opt_journal_checksum, Opt_journal_async_commit, Opt_abort, Opt_data_journal, Opt_data_ordered, Opt_data_writeback, Opt_data_err_abort, Opt_data_err_ignore, Opt_test_dummy_encryption, Opt_inlinecrypt...