Subject: Re: bug#41702: `guix environment` performance issues

From: Lars-Dominik Braun <[email-masked]>
Date: Mon, 20 Jul 2020 11:50:59 +0200

Hi Ludo,

a new version has been released, so here is the updated patchset. I’m not sure
if it’s possible to make the #:nodelay optional somehow, i.e. retaining
compatibility with guile-ssh<0.13.0. For now there’s a hard feature check.

Lars

From 42ff75c9d4da4eb2aeece96119ae5a65a9ccac82 Mon Sep 17 00:00:00 2001
From: Lars-Dominik Braun <[email-masked]>
Date: Mon, 20 Jul 2020 11:27:35 +0200
Subject: [PATCH 1/2] gnu: guile-ssh: Update to 0.13.0.

* gnu/packages/ssh.scm (guile-ssh): Update to 0.13.0.
---
 gnu/packages/ssh.scm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gnu/packages/ssh.scm b/gnu/packages/ssh.scm
index a612b9dd15..50316ea1be 100644
--- a/gnu/packages/ssh.scm
+++ b/gnu/packages/ssh.scm
@@ -297,7 +297,7 @@ Additionally, various channel-specific options can be negotiated.")
 (define-public guile-ssh
   (package
     (name "guile-ssh")
-    (version "0.12.0")
+    (version "0.13.0")
     (home-page "https://github.com/artyom-poptsov/guile-ssh")
     (source (origin
               (method git-fetch)
@@ -307,7 +307,7 @@ Additionally, various channel-specific options can be negotiated.")
               (file-name (string-append name "-" version ".tar.gz"))
               (sha256
                (base32
-                "054hd9rzfhb48gc1hw3rphhp0cnnd4bs5qmidy5ygsyvy9ravlad"))
+                "1q96h98p6x7ah6nc0d2wfx503fmsj36riv9ka9s79z3lzwaf0k26"))
               (modules '((guix build utils)))))
     (build-system gnu-build-system)
     (outputs '("out" "debug"))
-- 
2.20.1

From 6a18c9a4533075d1ee9795777a998fde3e64030f Mon Sep 17 00:00:00 2001
From: Lars-Dominik Braun <[email-masked]>
Date: Mon, 20 Jul 2020 11:28:51 +0200
Subject: [PATCH 2/2] guix: Speed up RPC via SSH connections.

See issue #41702

* guix/ssh.scm (open-ssh-session): Enable #:nodelay.
* m4/guix.m4 (GUIX_CHECK_GUILE_SSH): Add feature check for this new parameter.
---
 guix/ssh.scm | 5 ++++-
 m4/guix.m4   | 6 ++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/guix/ssh.scm b/guix/ssh.scm
index 2d7ca7d01d..3bffb0b525 100644
--- a/guix/ssh.scm
+++ b/guix/ssh.scm
@@ -129,7 +129,10 @@ Throw an error on failure."
                                ;; We need lightweight compression when
                                ;; exchanging full archives.
                                #:compression compression
-                               #:compression-level 3)))
+                               #:compression-level 3
+
+                               ;; Speed up RPC.
+                               #:nodelay #t)))
 
     ;; Honor ~/.ssh/config.
     (session-parse-config! session)
diff --git a/m4/guix.m4 b/m4/guix.m4
index 7c27ae74df..cce03045db 100644
--- a/m4/guix.m4
+++ b/m4/guix.m4
@@ -142,14 +142,16 @@ dnl GUIX_CHECK_GUILE_SSH
 dnl
 dnl Check whether a recent-enough Guile-SSH is available.
 AC_DEFUN([GUIX_CHECK_GUILE_SSH], [
-  dnl Check whether 'userauth-gssapi!' (introduced in 0.12.0) is present.
+  dnl Check whether '#:nodelay' paramater to 'make-session' (introduced in
+  dnl 0.13.0) is present.
   AC_CACHE_CHECK([whether Guile-SSH is available and recent enough],
     [guix_cv_have_recent_guile_ssh],
     [GUILE_CHECK([retval],
       [(and (@ (ssh channel) channel-send-eof)
             (@ (ssh popen) open-remote-pipe)
             (@ (ssh dist node) node-eval)
-            (@ (ssh auth) userauth-gssapi!))])
+            (@ (ssh auth) userauth-gssapi!)
+            ((@ (ssh session) make-session) #:nodelay #t))])
      if test "$retval" = 0; then
        guix_cv_have_recent_guile_ssh="yes"
      else
-- 
2.20.1