Thread overview
Assistance with >~95% CPU usage when calling pread64 when using LUKS
Mar 10
abraunegg
Mar 11
abraunegg
Mar 11
abraunegg
March 10
Hi all,

I was wondering if I could seek some guidance on tracking an issue down.

As the current maintainer of the Linux OneDrive client (https://github.com/abraunegg) I have two open issues which are both high CPU, on Ubuntu, where both file systems reside on a LUKS encrypted volume.

* https://github.com/abraunegg/onedrive/issues/394
* https://github.com/abraunegg/onedrive/issues/404

Essentially, from the strace, it appears that the application is spending nearly all of it's time calling pread64.

Currently I am also not able to replicate this issue locally.

Is there any sort of extra debugging that I could do to understand what else is going on, or can you suggest any code changes which may improve the reading of files?

Any suggestions are greatly appreciated.
March 10
On Sunday, 10 March 2019 at 19:59:40 UTC, abraunegg wrote:
> Is there any sort of extra debugging that I could do to understand what else is going on, or can you suggest any code changes which may improve the reading of files?

I would think about finding a better solution than this one:
https://github.com/abraunegg/onedrive/blob/master/src/util.d#L140
March 11
On Sunday, 10 March 2019 at 20:55:16 UTC, Boris-Barboris wrote:
> On Sunday, 10 March 2019 at 19:59:40 UTC, abraunegg wrote:
>> Is there any sort of extra debugging that I could do to understand what else is going on, or can you suggest any code changes which may improve the reading of files?
>
> I would think about finding a better solution than this one:
> https://github.com/abraunegg/onedrive/blob/master/src/util.d#L140

Thanks - yes that function / check could be better I agree, however that is not called when the system is simply checking the status of any changed files & folders. That is only used when checking if a 'new file' should be uploaded.

In the issues posted, it simply seems to be the checking of each and every file / folder when there is zero rate of change - the only thing here is the enumeration of DirEntry items.
March 11
On Monday, 11 March 2019 at 03:43:19 UTC, abraunegg wrote:
> Thanks - yes that function / check could be better I agree, however that is not called when the system is simply checking the status of any changed files & folders. That is only used when checking if a 'new file' should be uploaded.
>
> In the issues posted, it simply seems to be the checking of each and every file / folder when there is zero rate of change - the only thing here is the enumeration of DirEntry items.

Sorry, I skimmed through the issues quickly. Given the sparsity of info in the logs, I would be caughtious in assuming the program internal state.
I can recommend trying to compile an easy to use instruction for "callgrind" trace generation (there is a good page on dlang wiki about it), wich, given a debug build of a program, should give you an insight about what's happening.

I don't think there's much use of statically analyzing a source code, you should try to extract more runtime info from the issue reporters.
March 11
On Monday, 11 March 2019 at 08:29:56 UTC, Boris-Barboris wrote:
> Sorry, I skimmed through the issues quickly. Given the sparsity of info in the logs, I would be caughtious in assuming the program internal state.

Agreed there - I have a feeling it is related to the use of encryption & the overheads with that.

> I can recommend trying to compile an easy to use instruction for "callgrind" trace generation (there is a good page on dlang wiki about it), wich, given a debug build of a program, should give you an insight about what's happening.
>
> I don't think there's much use of statically analyzing a source code, you should try to extract more runtime info from the issue reporters.

Thanks - will look into that.