From: David Gibson <david@gibson.dropbear.id.au>
To: Stefano Brivio <sbrivio@redhat.com>
Cc: passt-dev@passt.top
Subject: Re: [PATCH v3 00/18] RFC: Unify and simplify tap send path
Date: Wed, 25 Jan 2023 14:13:44 +1100 [thread overview]
Message-ID: <Y9CeaIb8i+27zn18@yekko> (raw)
In-Reply-To: <20230124222043.281ef58c@elisabeth>
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On Tue, Jan 24, 2023 at 10:20:43PM +0100, Stefano Brivio wrote:
> On Fri, 6 Jan 2023 11:43:04 +1100
> David Gibson <david@gibson.dropbear.id.au> wrote:
>
> > Although we have an abstraction for the "slow path" (DHCP, NDP) guest
> > bound packets, the TCP and UDP forwarding paths write directly to the
> > tap fd. However, it turns out how they send frames to the tap device
> > is more similar than it originally appears.
> >
> > This series unifies the low-level tap send functions for TCP and UDP,
> > and makes some clean ups along the way.
> >
> > This is based on my earlier outstanding series.
>
> For some reason, performance tests consistently get stuck (both TCP and
> UDP, sometimes throughput, sometimes latency tests) with this series,
> and not without it, but I don't see any possible relationship with that.
Drat, I didn't encounter that. Any chance you could bisect to figure
out which patch specifically seems to trigger it?
I wonder if this could be related to the stalls I'm debugging,
although those didn't appear on the perf tests and also occur on
main. I have now discovered they seem to be masked by large socket
buffer sizes - more info at https://bugs.passt.top/show_bug.cgi?id=41
> I checked debug output and I couldn't find anything obviously wrong
> there. I just started checking packet captures now...
Hrm, probably not then. The stalls I'm seeing are associated with
lots of partial sends.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2023-01-25 6:24 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-06 0:43 [PATCH v3 00/18] RFC: Unify and simplify tap send path David Gibson
2023-01-06 0:43 ` [PATCH v3 01/18] pcap: Introduce pcap_frame() helper David Gibson
2023-01-06 0:43 ` [PATCH v3 02/18] pcap: Replace pcapm() with pcap_multiple() David Gibson
2023-01-06 0:43 ` [PATCH v3 03/18] tcp: Combine two parts of passt tap send path together David Gibson
2023-01-06 0:43 ` [PATCH v3 04/18] tcp: Don't compute total bytes in a message until we need it David Gibson
2023-01-06 0:43 ` [PATCH v3 05/18] tcp: Improve interface to tcp_l2_buf_flush() David Gibson
2023-01-06 0:43 ` [PATCH v3 06/18] tcp: Combine two parts of pasta tap send path together David Gibson
2023-02-13 1:13 ` Stefano Brivio
2023-01-06 0:43 ` [PATCH v3 07/18] tap, tcp: Move tap send path to tap.c David Gibson
2023-01-06 0:43 ` [PATCH v3 08/18] util: Introduce hton*_constant() in place of #ifdefs David Gibson
2023-01-06 0:43 ` [PATCH v3 09/18] tcp, udp: Use named field initializers in iov_init functions David Gibson
2023-01-06 0:43 ` [PATCH v3 10/18] util: Parameterize ethernet header initializer macro David Gibson
2023-01-06 0:43 ` [PATCH v3 11/18] tcp: Remove redundant and incorrect initialization from *_iov_init() David Gibson
2023-01-06 0:43 ` [PATCH v3 12/18] tcp: Consolidate calculation of total frame size David Gibson
2023-01-06 0:43 ` [PATCH v3 13/18] tap: Add "tap headers" abstraction David Gibson
2023-01-06 0:43 ` [PATCH v3 14/18] tcp: Use abstracted tap header David Gibson
2023-01-06 0:43 ` [PATCH v3 15/18] tap: Use different io vector bases depending on tap type David Gibson
2023-01-06 0:43 ` [PATCH v3 16/18] udp: Use abstracted tap header David Gibson
2023-01-06 0:43 ` [PATCH v3 17/18] tap: Improve handling of partial frame sends David Gibson
2023-01-06 0:43 ` [PATCH v3 18/18] udp: Use tap_send_frames() David Gibson
2023-01-24 21:20 ` [PATCH v3 00/18] RFC: Unify and simplify tap send path Stefano Brivio
2023-01-25 3:13 ` David Gibson [this message]
2023-01-25 23:21 ` Stefano Brivio
2023-02-13 1:14 ` Stefano Brivio
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