Date: Tue, 2 Jun 2020 20:42:45 +0000 (UTC) From: Alexander Motin <mav@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r361736 - stable/11/sys/dev/iscsi Message-ID: <202006022042.052KgjAi056537@repo.freebsd.org>
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Author: mav Date: Tue Jun 2 20:42:45 2020 New Revision: 361736 URL: https://svnweb.freebsd.org/changeset/base/361736 Log: MFC 361400: Do not try to fill socket send buffer to the last byte. Setting so_snd.sb_lowat to at least 1/8 of the socket buffer size allows send thread more actively use PDUs coalescing, that dramatically reduces TCP lock congestion and number of context switches, when the socket is full and PDUs are small. Modified: stable/11/sys/dev/iscsi/icl_soft.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/dev/iscsi/icl_soft.c ============================================================================== --- stable/11/sys/dev/iscsi/icl_soft.c Tue Jun 2 20:42:25 2020 (r361735) +++ stable/11/sys/dev/iscsi/icl_soft.c Tue Jun 2 20:42:45 2020 (r361736) @@ -913,7 +913,8 @@ icl_conn_send_pdus(struct icl_conn *ic, struct icl_pdu "have %ld, need %ld", available, size); #endif - so->so_snd.sb_lowat = size; + so->so_snd.sb_lowat = max(size, + so->so_snd.sb_hiwat / 8); SOCKBUF_UNLOCK(&so->so_snd); return; }
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