On 2024-10-10 13:47, Morten Brørup wrote:
From: Mattias Rönnblom [mailto:hof...@lysator.liu.se]
Sent: Thursday, 10 October 2024 12.40
On 2024-10-10 00:15, Morten Brørup wrote:
From: Mattias Rönnblom [mailto:mattias.ronnb...@ericsson.com]
Sent: Wednesday, 18 September 2024 10.26
Introduce DPDK per-lcore id variables, or lcore variables for short.
An lcore variable has one value for every current and future lcore
id-equipped thread.
The primary <rte_lcore_var.h> use case is for statically allocating
small, frequently-accessed data structures, for which one instance
should exist for each lcore.
Lcore variables are similar to thread-local storage (TLS, e.g., C11
_Thread_local), but decoupling the values' life time with that of
the
threads.
Lcore variables are also similar in terms of functionality provided
by
FreeBSD kernel's DPCPU_*() family of macros and the associated
build-time machinery. DPCPU uses linker scripts, which effectively
prevents the reuse of its, otherwise seemingly viable, approach.
The currently-prevailing way to solve the same problem as lcore
variables is to keep a module's per-lcore data as RTE_MAX_LCORE-
sized
array of cache-aligned, RTE_CACHE_GUARDed structs. The benefit of
lcore variables over this approach is that data related to the same
lcore now is close (spatially, in memory), rather than data used by
the same module, which in turn avoid excessive use of padding,
polluting caches with unused data.
Signed-off-by: Mattias Rönnblom <mattias.ronnb...@ericsson.com>
Acked-by: Morten Brørup <m...@smartsharesystems.com>
--- /dev/null
+++ b/lib/eal/common/eal_common_lcore_var.c
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2024 Ericsson AB
+ */
+
+#include <inttypes.h>
+#include <stdlib.h>
+
+#ifdef RTE_EXEC_ENV_WINDOWS
+#include <malloc.h>
+#endif
From what I can read on the internet, max_align_t is missing in
stddef.h in MSVC [1], so try adding this to fix the Windows CI
compilation failure:
#ifdef RTE_TOOLCHAIN_MSVC
#include <cstddef>
#endif
Please excuse my MSVC ignorance, but will this work in C? Looks like
C++.
I have no clue. Just parroting what Microsoft says on the internet.
You can try it out and see if the CI accepts it.
It wouldn't make sense if that worked, so I'll go for this instead:
#ifdef RTE_TOOLCHAIN_MSVC
/* MSVC <stddef.h> is missing the max_align_t typedef */
align = alignof(double);
#else
align = alignof(max_align_t);
#endif
Thanks for pointing out this issue.
[1]: https://learn.microsoft.com/en-ie/answers/questions/1726147/why-
max-align-t-not-defined-in-stddef-h-in-windows
I would like to see this series go into 24.11, and then it needs to work for
MSVC too.
@Tyler, any better suggestions for fixing the missing max_align_t in stddef.h?
