diff mbox series

[net-next,v3,6/7] selftests: net: Add busy_poll_test

Message ID 20241101004846.32532-7-jdamato@fastly.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series Suspend IRQs during application busy periods | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; GEN HAS DIFF 2 files changed, 19 insertions(+);
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 5 this patch: 5
netdev/build_tools success Errors and warnings before: 0 (+0) this patch: 0 (+0)
netdev/cc_maintainers success CCed 7 of 7 maintainers
netdev/build_clang success Errors and warnings before: 4 this patch: 4
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success net selftest script(s) already in Makefile
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 8 this patch: 8
netdev/checkpatch warning WARNING: added, moved or deleted file(s), does MAINTAINERS need updating? WARNING: line length of 113 exceeds 80 columns WARNING: line length of 130 exceeds 80 columns WARNING: line length of 216 exceeds 80 columns WARNING: line length of 82 exceeds 80 columns WARNING: line length of 89 exceeds 80 columns WARNING: line length of 93 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest fail net-next-2024-11-01--06-00 (tests: 780)

Commit Message

Joe Damato Nov. 1, 2024, 12:48 a.m. UTC
Add an epoll busy poll test using netdevsim.

This test is comprised of:
  - busy_poller (via busy_poller.c)
  - busy_poll_test.sh which loads netdevsim, sets up network namespaces,
    and runs busy_poller to receive data and netcat to send data.

The selftest tests two different scenarios:
  - busy poll (the pre-existing version in the kernel)
  - busy poll with suspend enabled (what this series adds)

The data transmit is a 1MiB temporary file generated from /dev/urandom
and the test is considered passing if the md5sum of the input file to
netcat matches the md5sum of the output file from busy_poller.

netdevsim was chosen instead of veth due to netdevsim's support for
netdev-genl.

For now, this test uses the functionality that netdevim provides. In the
future, perhaps netdevsim can be extended to emulate device IRQs to more
thoroughly test all pre-existing kernel options (like defer_hard_irqs)
and suspend.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Co-developed-by: Martin Karsten <mkarsten@uwaterloo.ca>
Signed-off-by: Martin Karsten <mkarsten@uwaterloo.ca>
---
 v3:
   - New in v3

 tools/testing/selftests/net/.gitignore        |   1 +
 tools/testing/selftests/net/Makefile          |   2 +
 tools/testing/selftests/net/busy_poll_test.sh | 164 ++++++++++++
 tools/testing/selftests/net/busy_poller.c     | 245 ++++++++++++++++++
 4 files changed, 412 insertions(+)
 create mode 100755 tools/testing/selftests/net/busy_poll_test.sh
 create mode 100644 tools/testing/selftests/net/busy_poller.c

Comments

Jakub Kicinski Nov. 1, 2024, 1:34 p.m. UTC | #1
On Fri,  1 Nov 2024 00:48:33 +0000 Joe Damato wrote:
> +	ip netns exec nscl nc -N 192.168.1.1 48675 < $tmp_file

Thanks a lot for adding the test. Could you replace nc with socat or
a similar tool? There are multiple incompatible implementations of
netcat packaged by various distros, we get:

# selftests: net: busy_poll_test.sh
# nc: invalid option -- 'N'
# Ncat: Try `--help' or man(1) ncat for more information, usage options and help. QUITTING.

nc is a known PITA.

> +	# set the suspend parameter for the server via its IFIDX
> +
> +	DUMP_CMD="${YNL_PATH} --spec ${SPEC_PATH} --dump napi-get --json=\"{\\\"ifindex\\\": ${NSIM_DEV_1_IFIDX}}\" --output-json"
> +	NSIM_DEV_1_NAPIID=$(ip netns exec nssv bash -c "$DUMP_CMD")
> +	NSIM_DEV_1_NAPIID=$(echo $NSIM_DEV_1_NAPIID | jq '.[] | .id')
> +
> +	SUSPEND_CMD="${YNL_PATH} --spec ${SPEC_PATH} --do napi-set --json=\"{\\\"id\\\": ${NSIM_DEV_1_NAPIID}, \\\"irq-suspend-timeout\\\": 20000000, \\\"gro-flush-timeout\\\": 50000, \\\"defer-hard-irqs\\\": 100}\""
> +	NSIM_DEV_1_SETCONFIG=$(ip netns exec nssv bash -c "$SUSPEND_CMD")

Can you try to run this test in installed mode?

https://docs.kernel.org/dev-tools/kselftest.html#install-selftests

IIRC YNL moves around when we install, you'd either need to do
autodetection of the path (see tools/testing/selftests/net/lib/py/ynl.py
and if you go down this route please move the helper which exports the
YNL variables to lib.sh so other tests can reuse); or teach the C code
to do the setup, you can link against YNL fairly easily (look at where
ncdevmem is added in the Makefile, it uses YNL)
Joe Damato Nov. 1, 2024, 8:15 p.m. UTC | #2
On Fri, Nov 01, 2024 at 06:34:26AM -0700, Jakub Kicinski wrote:
> On Fri,  1 Nov 2024 00:48:33 +0000 Joe Damato wrote:
> > +	ip netns exec nscl nc -N 192.168.1.1 48675 < $tmp_file
> 
> Thanks a lot for adding the test.

Thanks for the review.

> Could you replace nc with socat or
> a similar tool? There are multiple incompatible implementations of
> netcat packaged by various distros, we get:
> 
> # selftests: net: busy_poll_test.sh
> # nc: invalid option -- 'N'
> # Ncat: Try `--help' or man(1) ncat for more information, usage options and help. QUITTING.
> 
> nc is a known PITA.

OK, I've replaced with socat for the v4 I am working on. I've also
added some additional documentation to the FAQ in the cover letter
and the kernel documentation to help answer Sridhar's question
because it may be a question others have as well.

> > +	# set the suspend parameter for the server via its IFIDX
> > +
> > +	DUMP_CMD="${YNL_PATH} --spec ${SPEC_PATH} --dump napi-get --json=\"{\\\"ifindex\\\": ${NSIM_DEV_1_IFIDX}}\" --output-json"
> > +	NSIM_DEV_1_NAPIID=$(ip netns exec nssv bash -c "$DUMP_CMD")
> > +	NSIM_DEV_1_NAPIID=$(echo $NSIM_DEV_1_NAPIID | jq '.[] | .id')
> > +
> > +	SUSPEND_CMD="${YNL_PATH} --spec ${SPEC_PATH} --do napi-set --json=\"{\\\"id\\\": ${NSIM_DEV_1_NAPIID}, \\\"irq-suspend-timeout\\\": 20000000, \\\"gro-flush-timeout\\\": 50000, \\\"defer-hard-irqs\\\": 100}\""
> > +	NSIM_DEV_1_SETCONFIG=$(ip netns exec nssv bash -c "$SUSPEND_CMD")
> 
> Can you try to run this test in installed mode?
> 
> https://docs.kernel.org/dev-tools/kselftest.html#install-selftests
> 
> IIRC YNL moves around when we install, you'd either need to do
> autodetection of the path (see tools/testing/selftests/net/lib/py/ynl.py
> and if you go down this route please move the helper which exports the
> YNL variables to lib.sh so other tests can reuse); or teach the C code
> to do the setup, you can link against YNL fairly easily (look at where
> ncdevmem is added in the Makefile, it uses YNL)

I think I'm going to go the C route.

Just to make sure I'm following how to do this properly:
  - I've added busy_poller to YNL_GEN_FILES (and removed it from
    TEST_GEN_FILES)
  - It still needs to be run via the script (which sets up netdevsim
    etc), so I am leaving that script (busy_poll_test.sh) in
    TEST_PROGS. busy_poller is not intended to be run on its own for
    selftest purposes.

I am not sure if YNL_GEN_FILES are expected to run standalone when
invoked or if this will work as I expect it to (busy_poll_test.sh is
run):

  [...]
  TEST_PROGS += busy_poll_test.sh
  
  # YNL files, must be before "include ..lib.mk"
  YNL_GEN_FILES := ncdevmem busy_poller
  [...]

Doing the above: I am hoping that busy_poll_test.sh will be run
(which will use busy_poller) and that busy_poller won't be run on
its own.

Thanks for the guidance.
diff mbox series

Patch

diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
index 217d8b7a7365..85b0c4a2179f 100644
--- a/tools/testing/selftests/net/.gitignore
+++ b/tools/testing/selftests/net/.gitignore
@@ -2,6 +2,7 @@ 
 bind_bhash
 bind_timewait
 bind_wildcard
+busy_poller
 cmsg_sender
 diag_uid
 epoll_busy_poll
diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 26a4883a65c9..4b5f3d7d900b 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -69,6 +69,7 @@  TEST_GEN_FILES += hwtstamp_config rxtimestamp timestamping txtimestamp
 TEST_GEN_FILES += ipsec
 TEST_GEN_FILES += ioam6_parser
 TEST_GEN_FILES += gro
+TEST_GEN_FILES += busy_poller
 TEST_GEN_PROGS = reuseport_bpf reuseport_bpf_cpu reuseport_bpf_numa
 TEST_GEN_PROGS += reuseport_dualstack reuseaddr_conflict tls tun tap epoll_busy_poll
 TEST_GEN_FILES += toeplitz
@@ -96,6 +97,7 @@  TEST_PROGS += fdb_flush.sh
 TEST_PROGS += fq_band_pktlimit.sh
 TEST_PROGS += vlan_hw_filter.sh
 TEST_PROGS += bpf_offload.py
+TEST_PROGS += busy_poll_test.sh
 
 # YNL files, must be before "include ..lib.mk"
 YNL_GEN_FILES := ncdevmem
diff --git a/tools/testing/selftests/net/busy_poll_test.sh b/tools/testing/selftests/net/busy_poll_test.sh
new file mode 100755
index 000000000000..bf33737691a4
--- /dev/null
+++ b/tools/testing/selftests/net/busy_poll_test.sh
@@ -0,0 +1,164 @@ 
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-only
+source net_helper.sh
+
+NSIM_DEV_1_ID=$((256 + RANDOM % 256))
+NSIM_DEV_1_SYS=/sys/bus/netdevsim/devices/netdevsim$NSIM_DEV_1_ID
+NSIM_DEV_2_ID=$((512 + RANDOM % 256))
+NSIM_DEV_2_SYS=/sys/bus/netdevsim/devices/netdevsim$NSIM_DEV_2_ID
+
+NSIM_DEV_SYS_NEW=/sys/bus/netdevsim/new_device
+NSIM_DEV_SYS_DEL=/sys/bus/netdevsim/del_device
+NSIM_DEV_SYS_LINK=/sys/bus/netdevsim/link_device
+NSIM_DEV_SYS_UNLINK=/sys/bus/netdevsim/unlink_device
+
+YNL_PATH=$(realpath $(dirname ${0}))/../../../net/ynl/cli.py
+SPEC_PATH=$(realpath $(dirname ${0}))/../../../../Documentation/netlink/specs/netdev.yaml
+
+check_ynl()
+{
+	if [ ! -f ${YNL_PATH} ]; then
+		echo "YNL path invalid: ${YNL_PATH}"
+		exit 1
+	fi
+
+	if [ ! -f ${SPEC_PATH} ]; then
+		echo "spec path invalid: ${SPEC_PATH}"
+		exit 1
+	fi
+}
+
+setup_ns()
+{
+	set -e
+	ip netns add nssv
+	ip netns add nscl
+
+	NSIM_DEV_1_NAME=$(find $NSIM_DEV_1_SYS/net -maxdepth 1 -type d ! \
+		-path $NSIM_DEV_1_SYS/net -exec basename {} \;)
+	NSIM_DEV_2_NAME=$(find $NSIM_DEV_2_SYS/net -maxdepth 1 -type d ! \
+		-path $NSIM_DEV_2_SYS/net -exec basename {} \;)
+
+	# ensure the server has 1 queue
+	ethtool -L $NSIM_DEV_1_NAME combined 1 2>/dev/null
+
+	ip link set $NSIM_DEV_1_NAME netns nssv
+	ip link set $NSIM_DEV_2_NAME netns nscl
+
+	ip netns exec nssv ip addr add '192.168.1.1/24' dev $NSIM_DEV_1_NAME
+	ip netns exec nscl ip addr add '192.168.1.2/24' dev $NSIM_DEV_2_NAME
+
+	ip netns exec nssv ip link set dev $NSIM_DEV_1_NAME up
+	ip netns exec nscl ip link set dev $NSIM_DEV_2_NAME up
+
+	set +e
+}
+
+cleanup_ns()
+{
+	ip netns del nscl
+	ip netns del nssv
+}
+
+test_busypoll()
+{
+	tmp_file=$(mktemp)
+	out_file=$(mktemp)
+
+	# fill a test file with random data
+	dd if=/dev/urandom of=${tmp_file} bs=1M count=1 2> /dev/null
+
+	timeout -k 60s 60s ip netns exec nssv ./busy_poller -p48675 -b192.168.1.1 -m8 -u0 -P1 -g16 -o${out_file}&
+
+	wait_local_port_listen nssv 48675 tcp
+
+	ip netns exec nscl nc -N 192.168.1.1 48675 < $tmp_file
+
+	wait
+
+	tmp_file_md5sum=$(md5sum $tmp_file | cut -f1 -d' ')
+	out_file_md5sum=$(md5sum $out_file | cut -f1 -d' ')
+
+	if [ "$tmp_file_md5sum" = "$out_file_md5sum" ]; then
+		res=0
+	else
+		echo "md5sum mismatch"
+		echo "input file md5sum: ${tmp_file_md5sum}";
+		echo "output file md5sum: ${out_file_md5sum}";
+		res=1
+	fi
+
+	rm $out_file $tmp_file
+
+	return $res
+}
+
+test_busypoll_with_suspend()
+{
+	# set the suspend parameter for the server via its IFIDX
+
+	DUMP_CMD="${YNL_PATH} --spec ${SPEC_PATH} --dump napi-get --json=\"{\\\"ifindex\\\": ${NSIM_DEV_1_IFIDX}}\" --output-json"
+	NSIM_DEV_1_NAPIID=$(ip netns exec nssv bash -c "$DUMP_CMD")
+	NSIM_DEV_1_NAPIID=$(echo $NSIM_DEV_1_NAPIID | jq '.[] | .id')
+
+	SUSPEND_CMD="${YNL_PATH} --spec ${SPEC_PATH} --do napi-set --json=\"{\\\"id\\\": ${NSIM_DEV_1_NAPIID}, \\\"irq-suspend-timeout\\\": 20000000, \\\"gro-flush-timeout\\\": 50000, \\\"defer-hard-irqs\\\": 100}\""
+	NSIM_DEV_1_SETCONFIG=$(ip netns exec nssv bash -c "$SUSPEND_CMD")
+
+	test_busypoll
+	return $?
+}
+
+###
+### Code start
+###
+
+check_ynl
+
+modprobe netdevsim
+
+# linking
+
+echo $NSIM_DEV_1_ID > $NSIM_DEV_SYS_NEW
+echo $NSIM_DEV_2_ID > $NSIM_DEV_SYS_NEW
+udevadm settle
+
+setup_ns
+
+NSIM_DEV_1_FD=$((256 + RANDOM % 256))
+exec {NSIM_DEV_1_FD}</var/run/netns/nssv
+NSIM_DEV_1_IFIDX=$(ip netns exec nssv cat /sys/class/net/$NSIM_DEV_1_NAME/ifindex)
+
+NSIM_DEV_2_FD=$((256 + RANDOM % 256))
+exec {NSIM_DEV_2_FD}</var/run/netns/nscl
+NSIM_DEV_2_IFIDX=$(ip netns exec nscl cat /sys/class/net/$NSIM_DEV_2_NAME/ifindex)
+
+echo "$NSIM_DEV_1_FD:$NSIM_DEV_1_IFIDX $NSIM_DEV_2_FD:$NSIM_DEV_2_IFIDX" > $NSIM_DEV_SYS_LINK
+if [ $? -ne 0 ]; then
+	echo "linking netdevsim1 with netdevsim2 should succeed"
+	cleanup_ns
+	exit 1
+fi
+
+test_busypoll
+if [ $? -ne 0 ]; then
+	echo "test_busypoll failed"
+	cleanup_ns
+	exit 1
+fi
+
+test_busypoll_with_suspend
+if [ $? -ne 0 ]; then
+	echo "test_busypoll_with_suspend failed"
+	cleanup_ns
+	exit 1
+fi
+
+echo "$NSIM_DEV_1_FD:$NSIM_DEV_1_IFIDX" > $NSIM_DEV_SYS_UNLINK
+
+echo $NSIM_DEV_2_ID > $NSIM_DEV_SYS_DEL
+
+cleanup_ns
+
+modprobe -r netdevsim
+
+exit 0
diff --git a/tools/testing/selftests/net/busy_poller.c b/tools/testing/selftests/net/busy_poller.c
new file mode 100644
index 000000000000..b49d67ce0ca8
--- /dev/null
+++ b/tools/testing/selftests/net/busy_poller.c
@@ -0,0 +1,245 @@ 
+// SPDX-License-Identifier: GPL-2.0
+#include <assert.h>
+#include <errno.h>
+#include <error.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+#include <sys/ioctl.h>
+#include <sys/epoll.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+/* if the headers haven't been updated, we need to define some things */
+#if !defined(EPOLL_IOC_TYPE)
+struct epoll_params {
+	uint32_t busy_poll_usecs;
+	uint16_t busy_poll_budget;
+	uint8_t prefer_busy_poll;
+
+	/* pad the struct to a multiple of 64bits */
+	uint8_t __pad;
+};
+
+#define EPOLL_IOC_TYPE 0x8A
+#define EPIOCSPARAMS _IOW(EPOLL_IOC_TYPE, 0x01, struct epoll_params)
+#define EPIOCGPARAMS _IOR(EPOLL_IOC_TYPE, 0x02, struct epoll_params)
+#endif
+
+static uint32_t cfg_port = 8000;
+static struct in_addr cfg_bind_addr = { .s_addr = INADDR_ANY };
+static char *cfg_outfile;
+static int cfg_max_events = 8;
+
+/* busy poll params */
+static uint32_t cfg_busy_poll_usecs;
+static uint16_t cfg_busy_poll_budget;
+static uint8_t cfg_prefer_busy_poll;
+
+static void usage(const char *filepath)
+{
+	error(1, 0,
+	      "Usage: %s -p<port> -b<addr> -m<max_events> -u<busy_poll_usecs> -P<prefer_busy_poll> -g<busy_poll_budget> -o<outfile>",
+	      filepath);
+}
+
+static void parse_opts(int argc, char **argv)
+{
+	int ret;
+	int c;
+
+	if (argc <= 1)
+		usage(argv[0]);
+
+	while ((c = getopt(argc, argv, "p:m:b:u:P:g:o:")) != -1) {
+		switch (c) {
+		case 'u':
+			cfg_busy_poll_usecs = strtoul(optarg, NULL, 0);
+			if (cfg_busy_poll_usecs == ULONG_MAX ||
+			    cfg_busy_poll_usecs > UINT32_MAX)
+				error(1, ERANGE, "busy_poll_usecs too large");
+			break;
+		case 'P':
+			cfg_prefer_busy_poll = strtoul(optarg, NULL, 0);
+			if (cfg_prefer_busy_poll == ULONG_MAX ||
+			    cfg_prefer_busy_poll > 1)
+				error(1, ERANGE,
+				      "prefer busy poll should be 0 or 1");
+			break;
+		case 'g':
+			cfg_busy_poll_budget = strtoul(optarg, NULL, 0);
+			if (cfg_busy_poll_budget == ULONG_MAX ||
+			    cfg_busy_poll_budget > UINT16_MAX)
+				error(1, ERANGE,
+				      "busy poll budget must be [0, UINT16_MAX]");
+			break;
+		case 'p':
+			cfg_port = strtoul(optarg, NULL, 0);
+			if (cfg_port > UINT16_MAX)
+				error(1, ERANGE, "port must be <= 65535");
+			break;
+		case 'b':
+			ret = inet_aton(optarg, &cfg_bind_addr);
+			if (ret == 0)
+				error(1, errno,
+				      "bind address %s invalid", optarg);
+			break;
+		case 'o':
+			cfg_outfile = strdup(optarg);
+			if (!cfg_outfile)
+				error(1, 0, "outfile invalid");
+			break;
+		case 'm':
+			cfg_max_events = strtol(optarg, NULL, 0);
+
+			if (cfg_max_events == LONG_MIN ||
+			    cfg_max_events == LONG_MAX ||
+			    cfg_max_events <= 0)
+				error(1, ERANGE,
+				      "max events must be > 0 and < LONG_MAX");
+			break;
+		}
+	}
+
+	if (optind != argc)
+		usage(argv[0]);
+}
+
+static void epoll_ctl_add(int epfd, int fd, uint32_t events)
+{
+	struct epoll_event ev;
+
+	ev.events = events;
+	ev.data.fd = fd;
+	if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &ev) == -1)
+		error(1, errno, "epoll_ctl add fd: %d", fd);
+}
+
+static void setnonblock(int sockfd)
+{
+	int flags;
+
+	flags = fcntl(sockfd, F_GETFL, 0);
+
+	if (fcntl(sockfd, F_SETFL, flags | O_NONBLOCK) == -1)
+		error(1, errno, "unable to set socket to nonblocking mode");
+}
+
+static void write_chunk(int fd, char *buf, ssize_t buflen)
+{
+	ssize_t remaining = buflen;
+	char *buf_offset = buf;
+	ssize_t writelen = 0;
+	ssize_t write_result;
+
+	while (writelen < buflen) {
+		write_result = write(fd, buf_offset, remaining);
+		if (write_result == -1)
+			error(1, errno, "unable to write data to outfile");
+
+		writelen += write_result;
+		remaining -= write_result;
+		buf_offset += write_result;
+	}
+}
+
+static void run_poller(void)
+{
+	struct epoll_event events[cfg_max_events];
+	struct epoll_params epoll_params = {0};
+	struct sockaddr_in server_addr;
+	int i, epfd, nfds;
+	ssize_t readlen;
+	int outfile_fd;
+	char buf[1024];
+	int sockfd;
+	int conn;
+	int val;
+
+	outfile_fd = open(cfg_outfile, O_WRONLY | O_CREAT, 0644);
+	if (outfile_fd == -1)
+		error(1, errno, "unable to open outfile: %s", cfg_outfile);
+
+	sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+	if (sockfd == -1)
+		error(1, errno, "unable to create listen socket");
+
+	server_addr.sin_family = AF_INET;
+	server_addr.sin_port = htons(cfg_port);
+	server_addr.sin_addr = cfg_bind_addr;
+
+	epoll_params.busy_poll_usecs = cfg_busy_poll_usecs;
+	epoll_params.busy_poll_budget = cfg_busy_poll_budget;
+	epoll_params.prefer_busy_poll = cfg_prefer_busy_poll;
+	epoll_params.__pad = 0;
+
+	val = 1;
+	if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)))
+		error(1, errno, "poller setsockopt reuseaddr");
+
+	setnonblock(sockfd);
+
+	if (bind(sockfd, (struct sockaddr *)&server_addr,
+		 sizeof(struct sockaddr_in)))
+		error(0, errno, "poller bind to port: %d\n", cfg_port);
+
+	if (listen(sockfd, 1))
+		error(1, errno, "poller listen");
+
+	epfd = epoll_create1(0);
+	if (ioctl(epfd, EPIOCSPARAMS, &epoll_params) == -1)
+		error(1, errno, "unable to set busy poll params");
+
+	epoll_ctl_add(epfd, sockfd, EPOLLIN | EPOLLOUT | EPOLLET);
+
+	for (;;) {
+		nfds = epoll_wait(epfd, events, cfg_max_events, -1);
+		for (i = 0; i < nfds; i++) {
+			if (events[i].data.fd == sockfd) {
+				conn = accept(sockfd, NULL, NULL);
+				if (conn == -1)
+					error(1, errno,
+					      "accepting incoming connection failed");
+
+				setnonblock(conn);
+				epoll_ctl_add(epfd, conn,
+					      EPOLLIN | EPOLLET | EPOLLRDHUP |
+					      EPOLLHUP);
+			} else if (events[i].events & EPOLLIN) {
+				for (;;) {
+					readlen = read(events[i].data.fd, buf,
+						       sizeof(buf));
+					if (readlen > 0)
+						write_chunk(outfile_fd, buf,
+							    readlen);
+					else
+						break;
+				}
+			} else {
+				/* spurious event ? */
+			}
+			if (events[i].events & (EPOLLRDHUP | EPOLLHUP)) {
+				epoll_ctl(epfd, EPOLL_CTL_DEL,
+					  events[i].data.fd, NULL);
+				close(events[i].data.fd);
+				close(outfile_fd);
+				return;
+			}
+		}
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	parse_opts(argc, argv);
+	run_poller();
+	return 0;
+}