Messages in this thread | | | Subject | Re: Printk mulitple line message support | From | Huang Ying <> | Date | Tue, 15 Nov 2011 08:50:01 +0800 |
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On Mon, 2011-11-14 at 22:40 +0800, Joe Perches wrote: > On Mon, 2011-11-14 at 14:58 +0800, Huang Ying wrote: > > Hi, > > > > In most cases, printk only guarantees messages from different printk > > calling will not be interleaved between each other. But many printk > > users uses multiple line to form a complete message and call printk > > for each line. So the following situation is possible for two printk > > users running on two CPUs. > > > > line 1 of message from printk user1 > > line 1 of message from printk user2 > > line 2 of message from printk user1 > > line 2 of message from printk user2 > > > > This makes kernel log hard to read. One possible solution to this > > issue is to give a sequence number (or ID) to each complete message. > > So the above lines will be: > > > > {1}line 1 of message from printk user1 > > {2}line 1 of message from printk user2 > > {1}line 2 of message from printk user1 > > {2}line 2 of message from printk user2 > > > > Then some simple script can be used to group lines together according > > to sequence number in lines. > > > > What do you think about that? > > This makes the typical multi-part but non-interleaved > output difficult to read.
With a simple script, we can strip out the sequence # easily.
> How about determining if there is interleaving and > emitting sequence # only in those cases? > > Perhaps test the atomic for the last sequence #.
So we will have no sequence # prefix for printk user1's lines if printk user 2 comes in the middle? Something as follow?
line 1 of message from printk user1 {2}line 1 of message from printk user2 line 2 of message from printk user1 {2}line 2 of message from printk user2
This will make it hard for a script to sort the lines. Where should it insert lines from printk user2 in the sort result?
Best Regards, Huang Ying
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