On 3/6/2020 2:48 PM, David Marchand wrote:
> Since 18.05 and the memory subsystem rework, EAL reserves some big
> (unused) mappings.
>
> In testpmd, we have been locking all pages to avoid page faults during
> benchmark/performance regression tests [1].
> However, asking for locking all the pages triggers issues on FreeBSD [2]
> and becomes really heavy in some Linux configurations (see [3], [4]).
>
> This patch changes the behavior so that testpmd only lock pages
> containing .text by default.
>
> 1: https://git.dpdk.org/dpdk/commit/?id=1c036b16c284
> 2: https://git.dpdk.org/dpdk/commit/?id=fb7b8b32cd95
> 3: https://bugzilla.redhat.com/show_bug.cgi?id=1786923
> 4: http://mails.dpdk.org/archives/dev/2020-February/158477.html
>
> Signed-off-by: David Marchand <david.march...@redhat.com>
<...>
> @@ -3455,6 +3456,42 @@ signal_handler(int signum)
> }
> }
>
> +static void
> +lock_pages(const void *_addr, size_t _len, const char *prefix)
> +{
> + const void *addr;
> + size_t pagesize;
> + size_t len;
> +
> + /* While Linux does not care, FreeBSD mlock expects page aligned
> + * address (according to the man).
> + */
> + pagesize = sysconf(_SC_PAGESIZE);
> + addr = RTE_PTR_ALIGN_FLOOR(_addr, pagesize);
> + len = _len + ((uintptr_t)_addr & (pagesize - 1));
> + if (mlock(addr, len)) {
> + TESTPMD_LOG(NOTICE, "%s: mlock %p (0x%zx) aligned to %p (0x%zx)
> failed with error \"%s\"\n",
> + prefix, _addr, _len, addr, len, strerror(errno));
> + }
> +}
> +
> +static int
> +lock_text_cb(struct dl_phdr_info *info, __rte_unused size_t size,
> + __rte_unused void *data)
> +{
> + int i;
> +
> + for (i = 0; i < info->dlpi_phnum; i++) {
> + void *addr;
> +
> + if (info->dlpi_phdr[i].p_memsz == 0)
> + continue;
> + addr = (void *)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
> + lock_pages(addr, info->dlpi_phdr[i].p_memsz, info->dlpi_name);
> + }
> + return 0;
> +}
+1 to the idea, testpmd initialization was taking too lock without
'--no-mlockall', but this code looks complex for the application level.
We can do this for testpmd but does all applications need to do something
similar? If so can we have a solution on eal level instead?
