[lkml]   [2018]   [Mar]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] slub: Fix misleading 'age' in verbose slub prints

On 3/7/2018 11:52 PM, Matthew Wilcox wrote:
> On Wed, Mar 07, 2018 at 12:13:56PM -0600, Christopher Lameter wrote:
>> On Wed, 7 Mar 2018, Chintan Pandya wrote:
>>> In this case, object got freed later but 'age' shows
>>> otherwise. This could be because, while printing
>>> this info, we print allocation traces first and
>>> free traces thereafter. In between, if we get schedule
>>> out, (jiffies - t->when) could become meaningless.
>> Ok then get the jiffies earlier?
>>> So, simply print when the object was allocated/freed.
>> The tick value may not related to anything in the logs that is why the
>> "age" is there. How do I know how long ago the allocation was if I look at
>> the log and only see long and large number of ticks since bootup?
> I missed that the first read-through too. The trick is that there are two printks:
> [ 6044.170804] INFO: Allocated in binder_transaction+0x4b0/0x2448 age=731 cpu=3 pid=5314
> ...
> [ 6044.216696] INFO: Freed in binder_free_transaction+0x2c/0x58 age=735 cpu=6 pid=2079
> If you print the raw value, then you can do the subtraction yourself;
> if you've subtracted it from jiffies each time, you've at least introduced
> jitter, and possibly enough jitter to confuse and mislead.
This is exactly what I was thinking. But looking up 'age' is easy
compared to 'when' and this seems required as from Christopher's
reply. So, will raise new patch cleaning commit message a bit.

Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc. is a member of the Code Aurora Forum, a Linux Foundation
Collaborative Project

 \ /
  Last update: 2018-03-08 07:52    [W:0.031 / U:0.876 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site