netdev - Re: [PATCH net-next 3/5] selftests: drv-net: rss_ctx: test queue changes vs user RSS config

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Message-ID: <66894e1a6b087_12869e294de@willemb.c.googlers.com.notmuch>
Date: Sat, 06 Jul 2024 10:00:58 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Jakub Kicinski <kuba@...nel.org>, 
 davem@...emloft.net
Cc: netdev@...r.kernel.org, 
 edumazet@...gle.com, 
 pabeni@...hat.com, 
 petrm@...dia.com, 
 przemyslaw.kitszel@...el.com, 
 willemdebruijn.kernel@...il.com, 
 ecree.xilinx@...il.com, 
 Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH net-next 3/5] selftests: drv-net: rss_ctx: test queue
 changes vs user RSS config

Jakub Kicinski wrote:
> By default main RSS table should change to include all queues.
> When user sets a specific RSS config the driver should preserve it,
> even when queue count changes. Driver should refuse to deactivate
> queues used in the user-set RSS config.
> 
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>

> +def test_rss_queue_reconfigure(cfg, main_ctx=True):
> +    """Make sure queue changes can't override requested RSS config.
> +
> +    By default main RSS table should change to include all queues.
> +    When user sets a specific RSS config the driver should preserve it,
> +    even when queue count changes. Driver should refuse to deactivate
> +    queues used in the user-set RSS config.
> +    """
> +
> +    if not main_ctx:
> +        require_ntuple(cfg)
> +
> +    # Start with 4 queues, an arbitrary known number.
> +    try:
> +        qcnt = len(_get_rx_cnts(cfg))
> +        ethtool(f"-L {cfg.ifname} combined 4")
> +        defer(ethtool, f"-L {cfg.ifname} combined {qcnt}")
> +    except:
> +        raise KsftSkipEx("Not enough queues for the test or qstat not supported")
> +
> +    if main_ctx:
> +        ctx_id = 0
> +        ctx_ref = ""
> +    else:
> +        ctx_id = ethtool_create(cfg, "-X", "context new")
> +        ctx_ref = f"context {ctx_id}"
> +        defer(ethtool, f"-X {cfg.ifname} {ctx_ref} delete")
> +
> +    # Indirection table should be distributing to all queues.
> +    data = get_rss(cfg, context=ctx_id)
> +    ksft_eq(0, min(data['rss-indirection-table']))
> +    ksft_eq(3, max(data['rss-indirection-table']))
> +
> +    # Increase queues, indirection table should be distributing to all queues.
> +    # It's unclear whether tables of additional contexts should be reset, too.
> +    if main_ctx:
> +        ethtool(f"-L {cfg.ifname} combined 5")
> +        data = get_rss(cfg)
> +        ksft_eq(0, min(data['rss-indirection-table']))
> +        ksft_eq(4, max(data['rss-indirection-table']))
> +        ethtool(f"-L {cfg.ifname} combined 4")
> +
> +    # Configure the table explicitly
> +    port = rand_port()
> +    ethtool(f"-X {cfg.ifname} {ctx_ref} weight 1 0 0 1")
> +    if main_ctx:
> +        other_key = 'empty'
> +        defer(ethtool, f"-X {cfg.ifname} default")
> +    else:
> +        other_key = 'noise'
> +        flow = f"flow-type tcp{cfg.addr_ipver} dst-port {port} context {ctx_id}"
> +        ntuple = ethtool_create(cfg, "-N", flow)
> +        defer(ethtool, f"-N {cfg.ifname} delete {ntuple}")
> +
> +    _send_traffic_check(cfg, port, ctx_ref, { 'target': (0, 3),
> +                                              other_key: (1, 2) })

How come queues missing from the indir set in non-main context are not
empty (but noise)?

> +
> +    # We should be able to increase queues, but table should be left untouched
> +    ethtool(f"-L {cfg.ifname} combined 5")
> +    data = get_rss(cfg, context=ctx_id)
> +    ksft_eq({0, 3}, set(data['rss-indirection-table']))
> +
> +    _send_traffic_check(cfg, port, ctx_ref, { 'target': (0, 3),
> +                                              other_key: (1, 2, 4) })
> +
> +    # Setting queue count to 3 should fail, queue 3 is used
> +    try:
> +        ethtool(f"-L {cfg.ifname} combined 3")
> +    except CmdExitFailure:
> +        pass
> +    else:
> +        raise Exception(f"Driver didn't prevent us from deactivating a used queue (context {ctx_id})")
> +
> +