From: "Slavomir Kaslev (VMware)" <slavomir.kaslev@gmail.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org
Subject: [PATCH v12 07/13] trace-cmd: Use splice(2) for vsockets if available
Date: Tue, 18 Jun 2019 17:44:49 +0300 [thread overview]
Message-ID: <20190618144455.3954-8-slavomir.kaslev@gmail.com> (raw)
In-Reply-To: <20190618144455.3954-1-slavomir.kaslev@gmail.com>
From: Slavomir Kaslev <kaslevs@vmware.com>
Detect if splice(2) reading is supported for vsockets (Linux 4.20 and
later) and use it, or fallback to read/write-ing otherwise.
Signed-off-by: Slavomir Kaslev <kaslevs@vmware.com>
---
tracecmd/trace-record.c | 56 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 54 insertions(+), 2 deletions(-)
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index dfad8f2..f6e5c7e 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -2715,12 +2715,61 @@ static int open_vsock(unsigned int cid, unsigned int port)
return sd;
}
+
+static int try_splice_read_vsock(void)
+{
+ int ret, sd, brass[2];
+
+ sd = socket(AF_VSOCK, SOCK_STREAM, 0);
+ if (sd < 0)
+ return sd;
+
+ ret = pipe(brass);
+ if (ret < 0)
+ goto out_close_sd;
+
+ /*
+ * On kernels that don't support splice reading from vsockets
+ * this will fail with EINVAL, or ENOTCONN otherwise.
+ * Technically, it should never succeed but if it does, claim splice
+ * reading is supported.
+ */
+ ret = splice(sd, NULL, brass[1], NULL, 10, 0);
+ if (ret < 0)
+ ret = errno != EINVAL;
+ else
+ ret = 1;
+
+ close(brass[0]);
+ close(brass[1]);
+out_close_sd:
+ close(sd);
+ return ret;
+}
+
+static bool can_splice_read_vsock(void)
+{
+ static bool initialized, res;
+
+ if (initialized)
+ return res;
+
+ res = try_splice_read_vsock() > 0;
+ initialized = true;
+ return res;
+}
+
#else
static inline int open_vsock(unsigned int cid, unsigned int port)
{
die("vsock is not supported");
return -1;
}
+
+static bool can_splice_read_vsock(void)
+{
+ return false;
+}
#endif
static int do_accept(int sd)
@@ -2925,13 +2974,16 @@ create_recorder_instance(struct buffer_instance *instance, const char *file, int
if (is_guest(instance)) {
int fd;
+ unsigned int flags;
fd = open_vsock(instance->cid, instance->client_ports[cpu]);
if (fd < 0)
die("Failed to connect to agent");
- return tracecmd_create_recorder_virt(
- file, cpu, recorder_flags | TRACECMD_RECORD_NOSPLICE, fd);
+ flags = recorder_flags;
+ if (!can_splice_read_vsock())
+ flags |= TRACECMD_RECORD_NOSPLICE;
+ return tracecmd_create_recorder_virt(file, cpu, flags, fd);
}
if (brass)
--
2.20.1
next prev parent reply other threads:[~2019-06-18 14:45 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-18 14:44 [PATCH v12 00/13] Add VM kernel tracing over vsockets and FIFOs Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 01/13] trace-cmd: Make ports unsigned int Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 02/13] trace-cmd: Detect if vsockets are available Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 03/13] trace-cmd: Add tracecmd_create_recorder_virt() function Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 04/13] trace-cmd: Add VM tracing protocol messages Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 05/13] trace-cmd: Add buffer instance flags for tracing in guest and agent context Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 06/13] trace-cmd: Add VM kernel tracing over vsockets transport Slavomir Kaslev (VMware)
2019-06-18 14:44 ` Slavomir Kaslev (VMware) [this message]
2019-06-18 14:44 ` [PATCH v12 08/13] trace-cmd: Switch stop recording signal to SIGUSR1 Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 09/13] trace-cmd: Add `trace-cmd setup-guest` command Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 10/13] trace-cmd: Try to autodetect number of guest CPUs in setup-guest if not specified Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 11/13] trace-cmd: Add setup-guest flag for attaching FIFOs to the guest VM config Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 12/13] trace-cmd: Add splice() recording from FIFO without additional pipe buffer Slavomir Kaslev (VMware)
2019-06-18 14:44 ` [PATCH v12 13/13] trace-cmd: Add support for tracing VMware Workstation VMs by name Slavomir Kaslev (VMware)
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