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net/udp: Change conn->readahead to I/O buffer chain

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When using IOB queue to store readahead data, we use one IOB for each
UDP packet. Then if the packets are very small, like 10Bytes per packet,
we'll use ~1600 IOBs just for 16KB recv buffer size, which is wasteful
and dangerous. So change conn->readahead to a single IOB chain like TCP.

Benefits:
- Using memory and IOBs more efficiently (small packets are common in
  UDP)

Side effects:
- UDP recv buffer size may count the overhead
- A little bit drop in performance (<1%, more seek & copy)

Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
This commit is contained in:
Zhe Weng
2023-07-04 13:24:51 +08:00
committed by Xiang Xiao
parent 4b7604cf81
commit 075eb6a6d2
9 changed files with 115 additions and 62 deletions
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net/udp/udp_callback.c
+59 -30
View File
@@ -36,6 +36,7 @@
#include "devif/devif.h"
#include "udp/udp.h"
#include "utils/utils.h"
/****************************************************************************
* Private Functions
@@ -71,11 +72,11 @@ static uint16_t udp_datahandler(FAR struct net_driver_s *dev,
#endif
uint8_t src_addr_size;
FAR void *src_addr;
uint8_t offset = 0;
FAR void *src_addr;
int offset;
#if CONFIG_NET_RECV_BUFSIZE > 0
if (iob_get_queue_size(&conn->readahead) > conn->rcvbufs)
if (conn->readahead && conn->readahead->io_pktlen > conn->rcvbufs)
{
netdev_iob_release(dev);
#ifdef CONFIG_NET_STATISTICS
@@ -151,44 +152,72 @@ static uint16_t udp_datahandler(FAR struct net_driver_s *dev,
}
#endif /* CONFIG_NET_IPv4 */
/* Override the address info begin of io_data */
/* Copy the meta info into the I/O buffer chain, just before data.
* Layout: |datalen|ifindex|src_addr_size|src_addr|data|
*/
#ifdef CONFIG_NETDEV_IFINDEX
iob->io_data[offset++] = dev->d_ifindex;
#endif
iob->io_data[offset++] = src_addr_size;
memcpy(&iob->io_data[offset], src_addr, src_addr_size);
offset = (dev->d_appdata - iob->io_data) - iob->io_offset;
/* Trim l3/l4 offset */
iob = iob_trimhead(iob, (dev->d_appdata - iob->io_data) -
iob->io_offset);
/* Add the new I/O buffer chain to the tail of the read-ahead queue */
ret = iob_tryadd_queue(iob, &conn->readahead);
offset -= src_addr_size;
ret = iob_trycopyin(iob, src_addr, src_addr_size, offset, true);
if (ret < 0)
{
nerr("ERROR: Failed to queue the I/O buffer chain: %d\n", ret);
iob_free_chain(iob);
buflen = 0;
goto errout;
}
#ifdef CONFIG_NET_UDP_NOTIFIER
else
offset -= sizeof(src_addr_size);
ret = iob_trycopyin(iob, &src_addr_size, sizeof(src_addr_size),
offset, true);
if (ret < 0)
{
ninfo("Buffered %d bytes\n", buflen);
/* Provided notification(s) that additional UDP read-ahead data is
* available.
*/
udp_readahead_signal(conn);
goto errout;
}
#ifdef CONFIG_NETDEV_IFINDEX
offset -= sizeof(dev->d_ifindex);
ret = iob_trycopyin(iob, &dev->d_ifindex, sizeof(dev->d_ifindex),
offset, true);
if (ret < 0)
{
goto errout;
}
#endif
offset -= sizeof(buflen);
ret = iob_trycopyin(iob, (FAR const uint8_t *)&buflen, sizeof(buflen),
offset, true);
if (ret < 0)
{
goto errout;
}
/* Trim l3/l4 offset, src_addr + 4Bytes should be less than header size. */
DEBUGASSERT(offset >= 0);
iob = iob_trimhead(iob, offset);
/* Concat the iob to readahead */
net_iob_concat(&conn->readahead, &iob);
#ifdef CONFIG_NET_UDP_NOTIFIER
ninfo("Buffered %d bytes\n", buflen);
/* Provided notification(s) that additional UDP read-ahead data is
* available.
*/
udp_readahead_signal(conn);
#endif
netdev_iob_clear(dev);
return buflen;
errout:
nerr("ERROR: Failed to queue the I/O buffer chain: %d\n", ret);
netdev_iob_release(dev);
return 0;
}
/****************************************************************************