From c67266fbc07e8ceb383f76e8e639c80e94891fa7 Mon Sep 17 00:00:00 2001
From: "R. Sarmiento" <rafael.sarmiento@cscs.ch>
Date: Thu, 18 Jun 2026 10:34:47 +0200
Subject: [PATCH 1/3] add option to control cpu per engines

---
 ipcmagic/magics.py | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/ipcmagic/magics.py b/ipcmagic/magics.py
index 71034be..75190ff 100644
--- a/ipcmagic/magics.py
+++ b/ipcmagic/magics.py
@@ -20,11 +20,12 @@ class IPClusterMagics(Magics):
       %ipcluster --version
 
     Options:
-      -h --help                Show this screen.
-      -v --version             Show version.
-      -n --num_engines <int>   Number of engines
-      --launcher <str>         Job launcher (mpirun | srun | local)
-      --dask                   Create a dask.distributed cluster
+      -h --help                  Show this screen.
+      -v --version               Show version.
+      -n --num_engines <int>     Number of engines
+      -c --cpus_per_engine <int> Number of cpus per engine
+      --launcher <str>           Job launcher (mpirun | srun | local)
+      --dask                     Create a dask.distributed cluster
     """
 
     def __init__(self, shell):
@@ -51,7 +52,8 @@ def parse_args(self, line):
             'start': None,
             'stop': None,
             'launcher': 'srun',
-            'dask': False
+            'dask': False,
+            'cpus_per_engine': 1
         }
 
         given_args = {key: val for key, val in args.items() if val}
@@ -121,7 +123,7 @@ def _launch_engines_mpi(self):
         np_opt = launcher_np_opts[self.args.launcher]
         try:
             self.engines = run_command_async(
-                f'{self.args.launcher} {np_opt} {self.args.num_engines} ipengine '  # noqa: E501
+                f'{self.args.launcher} {np_opt} {self.args.num_engines} -c {self.args.cpus_per_engine} ipengine '  # noqa: E501
                 f'--location={hostname} --log-to-file')
         except FileNotFoundError:
             print(f'Launcher not supported in this system: '

From e0106f928f846dece30a4005621fb1bef05438d4 Mon Sep 17 00:00:00 2001
From: "R. Sarmiento" <rafael.sarmiento@cscs.ch>
Date: Thu, 18 Jun 2026 10:58:16 +0200
Subject: [PATCH 2/3] fix bug

---
 ipcmagic/magics.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/ipcmagic/magics.py b/ipcmagic/magics.py
index 75190ff..fd87da6 100644
--- a/ipcmagic/magics.py
+++ b/ipcmagic/magics.py
@@ -122,9 +122,12 @@ def _launch_engines_mpi(self):
         }
         np_opt = launcher_np_opts[self.args.launcher]
         try:
-            self.engines = run_command_async(
-                f'{self.args.launcher} {np_opt} {self.args.num_engines} -c {self.args.cpus_per_engine} ipengine '  # noqa: E501
-                f'--location={hostname} --log-to-file')
+            cmd = f'{self.args.launcher} {np_opt} {self.args.num_engines} '
+            if self.args.launcher == 'srun':
+                cmd += f'-c {self.args.cpus_per_engine} '
+
+            cmd += f'ipengine --location={hostname} --log-to-file'
+            self.engines = run_command_async(cmd)
         except FileNotFoundError:
             print(f'Launcher not supported in this system: '
                   f'{self.args.launcher}')

From a30a29a29afb6342f3e97c00b857f4eb3e061878 Mon Sep 17 00:00:00 2001
From: "R. Sarmiento" <rafael.sarmiento@cscs.ch>
Date: Thu, 18 Jun 2026 11:00:46 +0200
Subject: [PATCH 3/3] extend docstring

---
 ipcmagic/magics.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ipcmagic/magics.py b/ipcmagic/magics.py
index fd87da6..e5a03f2 100644
--- a/ipcmagic/magics.py
+++ b/ipcmagic/magics.py
@@ -23,7 +23,7 @@ class IPClusterMagics(Magics):
       -h --help                  Show this screen.
       -v --version               Show version.
       -n --num_engines <int>     Number of engines
-      -c --cpus_per_engine <int> Number of cpus per engine
+      -c --cpus_per_engine <int> Number of cpus per engine with srun
       --launcher <str>           Job launcher (mpirun | srun | local)
       --dask                     Create a dask.distributed cluster
     """