Commit 0b7bbc12 authored by Litao Jiao's avatar Litao Jiao
Browse files

net/smc: Tune the maximum size of virtually contiguous sndbufs or RMBs for SMC-R 

euleros inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I76JHC


CVE: NA

--------------------------------

If the receiver application reads data slower than the sender, the sender
may occur sending failures due to a full sndbufs, and the receiver may not
process the rmb timely which results in the sender unable to send data
immediately. Increasing the buffer size appropriately can help reduce the
probability of the above problems and increase throughput. Therefore, tune
the maximum size to 256M of virtually contiguous sndbufs or RMBs for SMC-R.

Signed-off-by: default avatarLitao Jiao <jiaolitao@sangfor.com.cn>
parent 4838ae72

Documentation/networking/smc-sysctl.rst

+4 −2
Original line number Diff line number Diff line
@@ -25,7 +25,8 @@ wmem - INTEGER 
	The default value inherits from net.ipv4.tcp_wmem[1].



	The minimum value is 16KiB and there is no hard limit for max value, but

	only allowed 512KiB for SMC-R and 1MiB for SMC-D.

        only allowed 512KiB for SMC-R using physically contiguous buffers, 256MiB

        for SMC-R using other buf type and 1MiB for SMC-D.



	Default: 16K
@@ -34,6 +35,7 @@ rmem - INTEGER 
	The default value inherits from net.ipv4.tcp_rmem[1].



	The minimum value is 16KiB and there is no hard limit for max value, but

	only allowed 512KiB for SMC-R and 1MiB for SMC-D.

	only allowed 512KiB for SMC-R using physically contiguous buffers, 256MiB

	for SMC-R using other buf type and 1MiB for SMC-D.



	Default: 128K

net/smc/smc_core.c

+22 −10
Original line number Diff line number Diff line
@@ -1394,17 +1394,17 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini) 
}



#define SMCD_DMBE_SIZES         6 /* 0 -> 16KB, 1 -> 32KB, .. 6 -> 1MB */

#define SMCR_RMBE_SIZES		5 /* 0 -> 16KB, 1 -> 32KB, .. 5 -> 512KB */

#define SMCR_RMBE_SIZES         14 /* 0 -> 16KB, 1 -> 32KB, .. 14 -> 256MB */



/* convert the RMB size into the compressed notation (minimum 16K, see

 * SMCD/R_DMBE_SIZES.

 * In contrast to plain ilog2, this rounds towards the next power of 2,

 * so the socket application gets at least its desired sndbuf / rcvbuf size.

 */

static u8 smc_compress_bufsize(int size, bool is_smcd, bool is_rmb)

static u8 smc_compress_bufsize(struct smc_link_group *lgr, int size, bool is_smcd, bool is_rmb)

{

	const unsigned int max_scat = SG_MAX_SINGLE_ALLOC * PAGE_SIZE;

	u8 compressed;

	u8 compressed, max_phy_compressed;



	if (size <= SMC_BUF_MIN_SIZE)

		return 0;
@@ -1413,9 +1413,21 @@ static u8 smc_compress_bufsize(int size, bool is_smcd, bool is_rmb) 
	compressed = min_t(u8, ilog2(size) + 1,

			is_smcd ? SMCD_DMBE_SIZES : SMCR_RMBE_SIZES);



	if (!is_smcd && is_rmb)

	if (!is_smcd && is_rmb && lgr->buf_type != SMCR_VIRT_CONT_BUFS) {

		max_phy_compressed = ilog2(max_scat >> 14);

		switch (lgr->buf_type) {

		case SMCR_MIXED_BUFS:

			if (compressed > max_phy_compressed)

				break;

			fallthrough;    // try phys continguous buf

		case SMCR_PHYS_CONT_BUFS:

			/* RMBs are backed by & limited to max size of scatterlists */

		compressed = min_t(u8, compressed, ilog2(max_scat >> 14));

			compressed = min_t(u8, compressed, max_phy_compressed);

			break;

		default:

			break;

		}

	}



	return compressed;

}
@@ -1761,7 +1773,7 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb) 
		/* use socket send buffer size (w/o overhead) as start value */

		sk_buf_size = smc->sk.sk_sndbuf;



	for (bufsize_short = smc_compress_bufsize(sk_buf_size, is_smcd, is_rmb);

	for (bufsize_short = smc_compress_bufsize(lgr, sk_buf_size, is_smcd, is_rmb);

	     bufsize_short >= 0; bufsize_short--) {

		if (is_rmb) {

			lock = &lgr->rmbs_lock;