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From: "Zhang, Qi Z" <qi.z.zhang@intel.com>
To: "Burakov, Anatoly" <anatoly.burakov@intel.com>, "dev@dpdk.org"
 <dev@dpdk.org>
CC: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
 "thomas@monjalon.net" <thomas@monjalon.net>, "Richardson, Bruce"
 <bruce.richardson@intel.com>
Thread-Topic: [dpdk-dev] [PATCH 0/8] Remove IPC threads
Thread-Index: AQHUBLS2PKFie3txNkSRAR62oKRw56RxvtGA
Date: Tue, 26 Jun 2018 01:19:25 +0000
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Subject: Re: [dpdk-dev] [PATCH 0/8] Remove IPC threads
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Hi Anatoly and Thomas:

Sorry for raise this late, but seems merge mp thread into interrupt thread =
gives problem to enable hotplug on secondary [1].

The issue is, when secondary want to attach a share device, it send request=
 to primary
Then primary is running in mp callback (mp thread) to attach device, it wil=
l call rte_malloc which get chance to increase heap that will do sync IPC,
You know, this is the limitation we can't do sync IPC in mp thread itself. =
so the solution is try to move real work to a separate thread which has no =
limitation to do sync IPC,=20
and interrupt thread is the good candidate, because we just need to call rt=
e_eal_set_alarm and we don't need to worry about the execution sequence.

But if we merge mp thread into interrupt thread, the solution will not work=
, we may need to create specific temporal thread to handle callback, but th=
is looks like some re-build which we already have.
So I think we need to revisit if we need to merge the thread before we have=
 a good solution for such kind of issue.

Thanks
Qi

[1] https://mails.dpdk.org/archives/dev/2018-June/105018.html


> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Anatoly Burakov
> Sent: Friday, June 15, 2018 10:25 PM
> To: dev@dpdk.org
> Cc: Ananyev, Konstantin <konstantin.ananyev@intel.com>;
> thomas@monjalon.net; Richardson, Bruce <bruce.richardson@intel.com>
> Subject: [dpdk-dev] [PATCH 0/8] Remove IPC threads
>=20
> As previously discussed [1], IPC threads need to be removed and their
> workload moved to interrupt thread.
>=20
> FreeBSD did not have an interrupt thread, nor did it support alarm API. T=
his
> patchset adds support for both on FreeBSD. FreeBSD interrupt thread is ba=
sed
> on kevent, FreeBSD's native event multiplexing mechanism similar to Linux=
's
> epoll.
>=20
> The patchset makes FreeBSD's interrupts and alarm work just enough to
> suffice for purposes of IPC, however there are really weird problems obse=
rved.
> Specifically, FreeBSD's kevent timers are really slow to trigger for some=
 reason,
> sleeping on a 10ms timer as much as 200ms before waking up. Interrupt
> handling on fd's is also a bit flaky.
>=20
> It has also been observed that both problems go away if we do not affinit=
ize
> master lcore (by commenting relevant code out [2]). It is not known why t=
hese
> problems are observed, nor it is clear what a solution might entail.
>=20
> For the purposes of making IPC work and having rudimentary support for
> alarm and interrupt API's, this patchset works fine. However, because of =
the
> above described issues, documentation will not be updated to indicate
> support for interrupts on FreeBSD at this time.
>=20
> [1] http://dpdk.org/dev/patchwork/patch/36579/
> [2] http://dpdk.org/browse/dpdk/tree/lib/librte_eal/bsdapp/eal/eal.c#n729
>=20
> Anatoly Burakov (4):
>   ipc: remove IPC thread for async requests
>   eal/bsdapp: add interrupt thread
>   eal/bsdapp: add alarm support
>   ipc: remove main IPC thread
>=20
> Jianfeng Tan (4):
>   eal/linux: use glibc malloc in alarm
>   eal/linux: use glibc malloc in interrupt handling
>   eal: bring forward init of interrupt handling
>   eal: add IPC type for interrupt thread
>=20
>  lib/librte_eal/bsdapp/eal/eal.c               |  10 +-
>  lib/librte_eal/bsdapp/eal/eal_alarm.c         | 299 +++++++++++-
>  lib/librte_eal/bsdapp/eal/eal_alarm_private.h |  19 +
>  lib/librte_eal/bsdapp/eal/eal_interrupts.c    | 460 +++++++++++++++++-
>  lib/librte_eal/common/eal_common_proc.c       | 243 ++++-----
>  .../common/include/rte_eal_interrupts.h       |   1 +
>  lib/librte_eal/linuxapp/eal/eal.c             |  10 +-
>  lib/librte_eal/linuxapp/eal/eal_alarm.c       |   9 +-
>  lib/librte_eal/linuxapp/eal/eal_interrupts.c  |  19 +-
>  test/test/test_interrupts.c                   |  29 +-
>  10 files changed, 899 insertions(+), 200 deletions(-)  create mode 10064=
4
> lib/librte_eal/bsdapp/eal/eal_alarm_private.h
>=20
> --
> 2.17.1