xdp-bench(8)

NAME
XDP-bench - a simple XDP benchmarking tool

SYNOPSIS

XDP-bench is a benchmarking utility for exercising the different operation modes of XDP. It is intended to be a simple program demonstrating the various operating modes; these include dropping packets, hairpin forwarding (using the XDP_TX return code), and redirection using the various in-kernel packet redirection facilities.

The drop and TX modes support various options to control whether packet data is touched (read or written) before being dropped or transmitted. The redirection modes support using the simple ifindex-based bpf_redirect helper, the bpf_redirect_map helper using a cpumap as its target, bpf_redirect_map using a devmap as its target, and the devmap's broadcast mode which allows redirecting to multiple devices.

There is more information on the meaning of the output in both default (terse) and extended output mode, in the Output Format Description section below.

  Running xdp-bench

The syntax for running xdp-bench is:
    Usage: xdp-bench COMMAND [options]
    COMMAND can be one of:
           drop           - Drop all packets on an interface
           tx             - Transmit packets back out on an interface (hairpin forwarding)
           redirect       - XDP redirect using the bpf_redirect() helper
           redirect-cpu   - XDP CPU redirect using BPF_MAP_TYPE_CPUMAP
           redirect-map   - XDP redirect using BPF_MAP_TYPE_DEVMAP
           redirect-multi - XDP multi-redirect using BPF_MAP_TYPE_DEVMAP and the BPF_F_BROADCAST flag

Each command, and its options are explained below. Or use xdp-bench COMMAND --help to see the options for each command.

The DROP command

In this mode, xdp-bench installs an XDP program on an interface that simply drops all packets. There are options to control what to do with the packet before dropping it (touch the packet data or not), as well as which statistics to gather. This is a basic benchmark for the baseline (best-case) performance of XDP on an interface.

The syntax for the drop command is:

xdp-bench drop [options] <ifname>

Where <ifname> is the name of the interface the XDP program should be installed on.

The supported options are:

  -p, --packet-operation <ACTION>

Specify which operation should be taken on the packet before dropping it. The following actions are available:
    no-touch		- Drop the packet without touching the packet data
    touch		- Read a field in the packet header before dropping
    swap-macs		- Swap the source and destination MAC addresses before dropping

Whether to touch the packet before dropping it can have a significant performance impact as this requires bringing packet data into the CPU cache (and flushing it back out if writing).

The default for this option is no-touch.

  -r, --rxq-stats

If set, the XDP program will also gather statistics on which receive queue index each packet was received on. This is displayed in the extended output mode along with per-CPU data (which, depending on the hardware configuration may or may not be equivalent).

  -i, --interval <SECONDS>

Set the polling interval for collecting all statistics and displaying them to the output. The unit of interval is in seconds.

  -e, --extended

Start xdp-bench in "extended" output mode. If not set, xdp-bench will start in "terse" mode. The output mode can be switched by hitting C-$ while the program is running. See also the Output Format Description section below.

  -m, --mode

Selects the XDP program mode (native or skb). Note that native XDP mode is the default, and loading the redirect program in skb manner is neither performant, nor recommended. However, this option is useful if the interface driver lacks native XDP support, or when simply testing the tool.

  -v, --verbose

Enable verbose logging. Supply twice to enable verbose logging from the underlying libxdp and libbpf libraries.

  --version

Show the application version and exit.

  -h, --help

Display a summary of the available options

The PASS command

In this mode, xdp-bench installs an XDP program on an interface that passes all packets to the network stack after processing them (returning XDP_PASS). There are options to control what to do with the packet before passing it (touch the packet data or not), as well as which statistics to gather. This is a basic benchmark for the overhead of installing an XDP program on an interface while still running the regular network stack.

The syntax for the pass command is:

xdp-bench pass [options] <ifname>

Where <ifname> is the name of the interface the XDP program should be installed on.

The supported options are:

  -p, --packet-operation <ACTION>

Specify which operation should be taken on the packet before passing it. The following actions are available:
    no-touch		- Pass the packet without touching the packet data
    touch		- Read a field in the packet header before passing
    swap-macs		- Swap the source and destination MAC addresses before passing

The default for this option is no-touch.

  -r, --rxq-stats

If set, the XDP program will also gather statistics on which receive queue index each packet was received on. This is displayed in the extended output mode along with per-CPU data (which, depending on the hardware configuration may or may not be equivalent).

  -i, --interval <SECONDS>

Set the polling interval for collecting all statistics and displaying them to the output. The unit of interval is in seconds.

  -e, --extended

Start xdp-bench in "extended" output mode. If not set, xdp-bench will start in "terse" mode. The output mode can be switched by hitting C-$ while the program is running. See also the Output Format Description section below.

  -m, --mode

Selects the XDP program mode (native or skb). Note that native XDP mode is the default, and loading the redirect program in skb manner is neither performant, nor recommended. However, this option is useful if the interface driver lacks native XDP support, or when simply testing the tool.

  -v, --verbose

Enable verbose logging. Supply twice to enable verbose logging from the underlying libxdp and libbpf libraries.

  --version

Show the application version and exit.

  -h, --help

Display a summary of the available options

The TX command

In this mode, xdp-bench installs an XDP program on an interface that performs so-called "hairpin forwarding", which means each packet is transmitted back out the same interface (using the XDP_TX return code).. There are options to control what to do with the packet before transmitting it (touch the packet data or not), as well as which statistics to gather.

The syntax for the tx command is:

xdp-bench tx [options] <ifname>

Where <ifname> is the name of the interface the XDP program should be installed on.

The supported options are:

  -p, --packet-operation <ACTION>

Specify which operation should be taken on the packet before transmitting it. The following actions are available:
    no-touch		- Transmit the packet without touching the packet data
    touch		- Read a field in the packet header before transmitting
    swap-macs		- Swap the source and destination MAC addresses before transmitting

To allow the packet to be successfully transmitted back to the sender, the MAC addresses have to be swapped, so that the source MAC matches the network device. However, there is a performance overhead in doing swapping, so this option allows this function to be turned off.

The default for this option is swap-macs.

  -r, --rxq-stats

If set, the XDP program will also gather statistics on which receive queue index each packet was received on. This is displayed in the extended output mode along with per-CPU data (which, depending on the hardware configuration may or may not be equivalent).

  -i, --interval <SECONDS>

Set the polling interval for collecting all statistics and displaying them to the output. The unit of interval is in seconds.

  -e, --extended

Start xdp-bench in "extended" output mode. If not set, xdp-bench will start in "terse" mode. The output mode can be switched by hitting C-$ while the program is running. See also the Output Format Description section below.

  -m, --mode

Selects the XDP program mode (native or skb). Note that native XDP mode is the default, and loading the redirect program in skb manner is neither performant, nor recommended. However, this option is useful if the interface driver lacks native XDP support, or when simply testing the tool.

  -v, --verbose

Enable verbose logging. Supply twice to enable verbose logging from the underlying libxdp and libbpf libraries.

  --version

Show the application version and exit.

  -h, --help

Display a summary of the available options

The REDIRECT command

In this mode, xdp-bench sets up packet redirection between the two interfaces supplied on the command line using the bpf_redirect BPF helper triggered on packet reception on the ingress interface.

The syntax for the redirect command is:

xdp-bench redirect [options] <ifname_in> <ifname_out>

Where <ifname_in> is the name of the input interface from where packets will be redirect to the output interface <ifname_out>.

The supported options are:

  -i, --interval <SECONDS>

Set the polling interval for collecting all statistics and displaying them to the output. The unit of interval is in seconds.

  -s, --stats

Enable statistics for successful redirection. This option comes with a per packet tracing overhead, for recording all successful redirections.

  -e, --extended

Start xdp-bench in "extended" output mode. If not set, xdp-bench will start in "terse" mode. The output mode can be switched by hitting C-$ while the program is running. See also the Output Format Description section below.

  -m, --mode

Selects the XDP program mode (native or skb). Note that native XDP mode is the default, and loading the redirect program in skb manner is neither performant, nor recommended. However, this option is useful if the interface driver lacks native XDP support, or when simply testing the tool.

  -v, --verbose

Enable verbose logging. Supply twice to enable verbose logging from the underlying libxdp and libbpf libraries.

  --version

Show the application version and exit.

  -h, --help

Display a summary of the available options

The REDIRECT-CPU command

In this mode, xdp-bench sets up packet redirection using the bpf_redirect_map BPF helper triggered on packet reception on the ingress interface, using a cpumap as its target. Hence, this tool can be used to redirect packets on an interface from one CPU to another. In addition to this, the tool then supports redirecting the packet to another output device when it is processed on the target CPU.

The syntax for the redirect-cpu command is:

xdp-bench redirect-cpu [options] <ifname> -c 0 ... -c N

Where <ifname> is the name of the input interface from where packets will be redirect to the target CPU list specified using -c.

The supported options are:

  -c, --cpu <CPU>

Specify a possible target CPU index. This option must be passed at least once, and can be passed multiple times to specify a list of CPUs. Which CPU is chosen for a given packet depends on the value of the --program-mode option, described below.

  -p, --program-mode <MODE>

Specify a program that embeds a predefined policy deciding how packets are redirected to different CPUs. The following options are available:
    no-touch		- Redirect without touching packet data
    touch		- Read packet data before redirecting
    round-robin	- Cycle between target CPUs in a round-robin fashion (for each packet)
    l4-proto		- Choose the target CPU based on the layer-4 protocol of packet
    l4-filter		- Like l4-proto, but drop UDP packets with destination port 9 (used by pktgen)
    l4-hash		- Use source and destination IP hashing to pick target CPU

The no-touch and touch modes always redirect packets to the same CPU (the first value supplied to --cpu). The round-robin and l4-hash modes distribute packets between all the CPUs supplied as --cpu arguments, while l4-proto and l4-filter send TCP and unrecognised packets to CPU index 0, UDP packets to CPU index 1 and ICMP packets to CPU index 2 (where the index refers to the order the actual CPUs are given on the command line).

The default for this option is l4-hash.

  -r --remote-action <ACTION>

If this option is set, a separate program is installed into the cpumap, which will be invoked on the remote CPU after the packet is processed there. The action can be either drop or pass which will drop the packet or pass it to the regular networking stack, respectively. Or it can be redirect, which will cause the packet to be redirected to another interface and transmitted out that interface on the remote CPU. If this option is set to redirect the target device must be specified using --redirect-device.

The default for this option is disabled.

  -r, --redirect-device <IFNAME>

Specify the device to redirect the packet to when it is received on the target CPU. Note that this option can only be specified with --remote-action redirect.

  -q, --qsize <PACKETS>

Set the queue size for the per-CPU cpumap ring buffer used for redirecting packets from multiple CPUs to one CPU. The default value is 2048 packets.

  -x, --stress-mode

Stress the cpumap implementation by deallocating and reallocating the cpumap ring buffer on each polling interval.

  -i, --interval <SECONDS>

Set the polling interval for collecting all statistics and displaying them to the output. The unit of interval is in seconds.

  -s, --stats

Enable statistics for successful redirection. This option comes with a per packet tracing overhead, for recording all successful redirections.

  -e, --extended

Start xdp-bench in "extended" output mode. If not set, xdp-bench will start in "terse" mode. The output mode can be switched by hitting C-$ while the program is running. See also the Output Format Description section below.

  -m, --mode

Selects the XDP program mode (native or skb). Note that native XDP mode is the default, and loading the redirect program in skb manner is neither performant, nor recommended. However, this option is useful if the interface driver lacks native XDP support, or when simply testing the tool.

  -v, --verbose

Enable verbose logging. Supply twice to enable verbose logging from the underlying libxdp and libbpf libraries.

  --version

Show the application version and exit.

  -h, --help

Display a summary of the available options

The REDIRECT-MAP command

In this mode, xdp-bench sets up packet redirection between two interfaces supplied on the command line using the bpf_redirect_map() BPF helper triggered on packet reception on the ingress interface, using a devmap as its target.

The syntax for the redirect-map command is:

xdp-bench redirect-map [options] <ifname_in> <ifname_out>

Where <ifname_in> is the name of the input interface from where packets will be redirect to the output interface <ifname_out>.

The supported options are:

  -X, --load-egress

Load a program in the devmap entry used for redirection, so that it is invoked after the packet is redirected to the target device, before it is transmitted out of the output interface. The remote program will update the packet data so its source MAC address matches the one of the destination interface.

  -i, --interval <SECONDS>

Set the polling interval for collecting all statistics and displaying them to the output. The unit of interval is in seconds.

  -s, --stats

Enable statistics for successful redirection. This option comes with a per packet tracing overhead, for recording all successful redirections.

  -e, --extended

Start xdp-bench in "extended" output mode. If not set, xdp-bench will start in "terse" mode. The output mode can be switched by hitting C-$ while the program is running. See also the Output Format Description section below.

  -m, --mode

Selects the XDP program mode (native or skb). Note that native XDP mode is the default, and loading the redirect program in skb manner is neither performant, nor recommended. However, this option is useful if the interface driver lacks native XDP support, or when simply testing the tool.

  -v, --verbose

Enable verbose logging. Supply twice to enable verbose logging from the underlying libxdp and libbpf libraries.

  --version

Show the application version and exit.

  -h, --help

Display a summary of the available options

The REDIRECT-MULTI command

In this mode, xdp-bench sets up one-to-many packet redirection between interfaces supplied on the command line, using the bpf_redirect_map BPF helper triggered on packet reception on the ingress interface, using a devmap as its target. The packet is broadcast to all output interfaces specified on the command line, using devmap's packet broadcast feature.

The syntax for the redirect-multi command is:

xdp-bench redirect-multi [options] <ifname_in> <ifname_out1> ... <ifname_outN>

Where <ifname_in> is the name of the input interface from where packets will be redirect to one or many output interface(s).

The supported options are:

  -X, --load-egress

Load a program in the devmap entry used for redirection, so that it is invoked after the packet is redirected to the target device, before it is transmitted out of the output interface. The remote program will update the packet data so its source MAC address matches the one of the destination interface.

  -i, --interval <SECONDS>

Set the polling interval for collecting all statistics and displaying them to the output. The unit of interval is in seconds.

  -s, --stats

Enable statistics for successful redirection. This option comes with a per packet tracing overhead, for recording all successful redirections.

  -e, --extended

Start xdp-bench in "extended" output mode. If not set, xdp-bench will start in "terse" mode. The output mode can be switched by hitting C-$ while the program is running. See also the Output Format Description section below.

  -m, --mode

Selects the XDP program mode (native or skb). Note that native XDP mode is the default, and loading the redirect program in skb manner is neither performant, nor recommended. However, this option is useful if the interface driver lacks native XDP support, or when simply testing the tool.

  -v, --verbose

Enable verbose logging. Supply twice to enable verbose logging from the underlying libxdp and libbpf libraries.

  --version

Show the application version and exit.

  -h, --help

Display a summary of the available options

Output Format Description

By default, redirect success statistics are disabled, use --stats to enable. The terse output mode is default, extended output mode can be activated using the --extended command line option.

SIGQUIT (Ctrl + \) can be used to switch the mode dynamically at runtime.

Terse mode displays at most the following fields:
    rx/s		Number of packets received per second
    redir/s	Number of packets successfully redirected per second
    err,drop/s	Aggregated count of errors per second (including dropped packets when not using the drop command)
    xmit/s	Number of packets transmitted on the output device per second

Extended output mode displays at most the following fields:
    FIELD		  DESCRIPTION
    receive	       Displays the number of packets received and errors encountered
    		       Whenever an error or packet drop occurs, details of per CPU error
    		       and drop statistics will be expanded inline in terse mode.
    				       pkt/s		- Packets received per second
    				       drop/s		- Packets dropped per second
    				       error/s		- Errors encountered per second
    				       redirect	- Displays the number of packets successfully redirected
    		       Errors encountered are expanded under redirect_err field
    		       Note that passing -s to enable it has a per packet overhead
    				       redir/s		- Packets redirected successfully per second
    redirect_err	  Displays the number of packets that failed redirection
    		       The errno is expanded under this field with per CPU count
    		       The recognized errors are:
    				       EINVAL:		Invalid redirection
    				       ENETDOWN:	Device being redirected to is down
    				       EMSGSIZE:	Packet length too large for device
    				       EOPNOTSUPP:	Operation not supported
    				       ENOSPC:		No space in ptr_ring of cpumap kthread
    				       error/s		- Packets that failed redirection per second
    enqueue to cpu N Displays the number of packets enqueued to bulk queue of CPU N
    		       Expands to cpu:FROM->N to display enqueue stats for each CPU enqueuing to CPU N
    		       Received packets can be associated with the CPU redirect program is enqueuing
    		       packets to.
    				       pkt/s		- Packets enqueued per second from other CPU to CPU N
    				       drop/s		- Packets dropped when trying to enqueue to CPU N
    				       bulk-avg	- Average number of packets processed for each event
    kthread	       Displays the number of packets processed in CPUMAP kthread for each CPU
    		       Packets consumed from ptr_ring in kthread, and its xdp_stats (after calling
    		       CPUMAP bpf prog) are expanded below this. xdp_stats are expanded as a total and
    		       then per-CPU to associate it to each CPU's pinned CPUMAP kthread.
    				       pkt/s		- Packets consumed per second from ptr_ring
    				       drop/s		- Packets dropped per second in kthread
    				       sched		- Number of times kthread called schedule()
    		       xdp_stats (also expands to per-CPU counts)
    				       pass/s		- XDP_PASS count for CPUMAP program execution
    				       drop/s		- XDP_DROP count for CPUMAP program execution
    				       redir/s		- XDP_REDIRECT count for CPUMAP program execution
    xdp_exception	  Displays xdp_exception tracepoint events
    		       This can occur due to internal driver errors, unrecognized
    		       XDP actions and due to explicit user trigger by use of XDP_ABORTED
    		       Each action is expanded below this field with its count
    				       hit/s		- Number of times the tracepoint was hit per second
    devmap_xmit      Displays devmap_xmit tracepoint events
    		       This tracepoint is invoked for successful transmissions on output
    		       device but these statistics are not available for generic XDP mode,
    		       hence they will be omitted from the output when using SKB mode
    				       xmit/s		- Number of packets that were transmitted per second
    				       drop/s		- Number of packets that failed transmissions per second
    				       drv_err/s	- Number of internal driver errors per second
    				       bulk-avg	- Average number of packets processed for each event

BUGS

Please report any bugs on Github: https://github.com/xdp-project/xdp-tools/issues

AUTHOR

Earlier xdp-redirect tools were written by Jesper Dangaard Brouer and John Fastabend. They were then rewritten to support more features by Kumar Kartikeya Dwivedi, who also ported them to xdp-tools together with Toke Høiland-Jørgensen. This man page was written by Kumar Kartikeya Dwivedi and Toke Høiland-Jørgensen.