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netdump: Buffer pages to avoid calling netdump_send() on each 4KB write.

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netdump waits for acknowledgement from the server for each write.  When
dumping page table pages, we perform many small writes, limiting
throughput.  Use the netdump client's buffer to buffer small contiguous
writes before calling netdump_send() to flush the MAXDUMPPGS-sized
buffer.  This results in a significant reduction in the time taken to
complete a netdump.

Submitted by:	Sam Gwydir <sam@samgwydir.com>
Reviewed by:	cem
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D20317
This commit is contained in:
markj 2019-05-31 18:29:12 +00:00
parent c5037e1d92
commit e9b44e8630
1 changed files with 26 additions and 5 deletions
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31
sys/netinet/netdump/netdump_client.c
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@ -130,6 +130,9 @@ static struct {
union kd_ip ndc_client;
union kd_ip ndc_gateway;
uint8_t ndc_af;
/* Runtime State */
off_t nd_tx_off;
size_t nd_buf_len;
} nd_conf;
#define nd_server nd_conf.ndc_server.in4
#define nd_client nd_conf.ndc_client.in4
@ -945,6 +948,14 @@ netdump_dumper(void *priv __unused, void *virtual,
virtual, (uintmax_t)offset, length);
if (virtual == NULL) {
if (nd_conf.nd_buf_len != 0) {
error = netdump_send(NETDUMP_VMCORE, nd_conf.nd_tx_off, nd_buf,
nd_conf.nd_buf_len);
if (error != 0) {
dump_failed = 1;
}
}
if (dump_failed != 0)
printf("failed to dump the kernel core\n");
else if (netdump_send(NETDUMP_FINISHED, 0, NULL, 0) != 0)
@ -957,12 +968,22 @@ netdump_dumper(void *priv __unused, void *virtual,
if (length > sizeof(nd_buf))
return (ENOSPC);
memmove(nd_buf, virtual, length);
error = netdump_send(NETDUMP_VMCORE, offset, nd_buf, length);
if (error != 0) {
dump_failed = 1;
return (error);
if (nd_conf.nd_buf_len + length > sizeof(nd_buf) ||
(nd_conf.nd_buf_len != 0 && nd_conf.nd_tx_off +
nd_conf.nd_buf_len != offset)) {
error = netdump_send(NETDUMP_VMCORE, nd_conf.nd_tx_off, nd_buf,
nd_conf.nd_buf_len);
if (error != 0) {
dump_failed = 1;
return (error);
}
nd_conf.nd_buf_len = 0;
nd_conf.nd_tx_off = offset;
}
memmove(nd_buf + nd_conf.nd_buf_len, virtual, length);
nd_conf.nd_buf_len += length;
return (0);
}