Re: Discussion at Linux Foundation Japan Symposium

[Masami Hiramatsu <mhiramat at redhat dot com>]

Hi Satoshi,

Thank you for reporting!

Satoshi OSHIMA wrote:
> Hi all,
> 
> Long time no see and sorry for my late report.
> 
> I attended 9th Linux Foundation Japan Symposium and 
> discussed on issues of systemtap project with Ted Ts'o, 
> James Bottomley and Jonathan Corbet.

FYI, we also discuss this topic on below bugzilla.
http://sourceware.org/bugzilla/show_bug.cgi?id=7042

There are links to videos of the symposium on that bugzilla.

> In my understanding, they demand the following things:
> 
> (1) Follow upstream first
> 
> Utrace and uprobe features are currently available only 
> on Fedora and Red Hat Enterprise Linux, since those 
> patches are not merged into upstream kernel yet.
> 
> my suggestion:
> 
> To reduce complaints of upstream kernel developers, 
> systemtap project may need to postpone adding new 
> uprobe features until getting utrace (and uprobe) 
> patch set accepted in mainline.
> 
> 
> (2) Maintain tapset
> 
> Systemtap users (including kernel developers) get 
> frustrated because tapsets often do not work on 
> the latest kernel. Moreover, sometimes users 
> have to fix the tapset incompatibility of kernels.
> 
> my suggestion:
> 
> If systemtap procjet can fix this kind of incompatibilities
> within a few hours or days as Myths about systemtap 
> on the wiki claims, releasing new systemtap minor release
> tarball for each upstream kernel release would help users.

Agreed, We have a weekly snapshot for it. however, that means
it could delay 1 week. And also, we should provide which
release can work on the latest kernel.

> (3) Make no debuginfo version
> 
> Systemtap always requires kernel debuginfo to use. 
> Unfortunately, it is hard for users of some distributions 
> to have debuginfo.
> 
> my suggestion:
> 
> If systemtap has a build option to make no debuginfo version,
> this complain will be reduced. I know we had had it before.
> We should provide it again.

As Prasad said, systemtap had supported no-dwarf mode, however,
currently it is disabled (due to uprobe issue?). I strongly
recommend to re-enable it only for kernel-space probes as soon as possible.

> (4) Have conversations frequently with Kernel Community
> 
> I understand that Frank has tried to communicate with upstream
> kernel community. However, it seems that developers of upstream 
> kernel feel it is not enough.
> 
> my suggestion:
> 
> I know that systemtap is a bit different from other part of
> the kernel. Usual kernel subsystem maintainers are chosen 
> on activities in lkml. On the other hand, systemtap maintainer's
> activities are invisible for almost all of the kernel developers.
> 
> This may be one of the reasons of their frastration.
> To solve this problem, we should periodically make announcements
> of systemtap update and require questions or comments.

>From Linux foundation video, I think we also would better work
with some kernel (subsystem) maintainers, and ask them
what they need to use systemtap easy.

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com