From: Cyrill Gorcunov <gorcunov@gmail.com> To: tml <tarantool-patches@dev.tarantool.org> Subject: Re: [Tarantool-patches] [PATCH] test/uint: fiber Date: Thu, 15 Oct 2020 19:28:07 +0300 [thread overview] Message-ID: <20201015162807.GF173841@grain> (raw) In-Reply-To: <20201015142827.386709-1-gorcunov@gmail.com> On Thu, Oct 15, 2020 at 05:28:27PM +0300, Cyrill Gorcunov wrote: > When optimization level increased we've found that > memset calls might be optimized, moreover there > were no check if calls themselves would override > the stack. > > Lets rework and use number of calls instead. Strictly > speaking the test is still a bit fragile and precise > testing would rather require asm level code. > > Repored-by: "Alexander V. Tikhonov" <avtikhon@tarantool.org> > Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> > --- > > branch gorcunov/unit-fiber I've force update the patch to match results file. --- From: Cyrill Gorcunov <gorcunov@gmail.com> Date: Thu, 15 Oct 2020 17:25:55 +0300 Subject: [PATCH] test/uint: fiber When optimization level increased we've found that memset calls might be optimized, moreover there were no check if calls themselves would override the stack. Lets rework and use number of calls instead. Strictly speaking the test is still a bit fragile and precise testing would rather require asm level code. Repored-by: "Alexander V. Tikhonov" <avtikhon@tarantool.org> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> --- test/unit/fiber.cc | 47 +++++++++++++++++++++++++++++++++++----------- 1 file changed, 36 insertions(+), 11 deletions(-) diff --git a/test/unit/fiber.cc b/test/unit/fiber.cc index b0dfc9b14..9c1a23bdd 100644 --- a/test/unit/fiber.cc +++ b/test/unit/fiber.cc @@ -1,10 +1,16 @@ +#include <unistd.h> + #include "memory.h" #include "fiber.h" #include "unit.h" #include "trivia/util.h" +static size_t stack_expand_limit; static struct fiber_attr default_attr; +static unsigned long page_size; +#define PAGE_4K 4096 + static int noop_f(va_list ap) { @@ -49,24 +55,38 @@ cancel_dead_f(va_list ap) return 0; } -static size_t stack_expand_limit; - static void NOINLINE -stack_expand(void *ptr) +stack_expand(unsigned long *ret, unsigned long nr_calls) { - char buf[2048]; - memset(buf, 0x45, 2048); - ptrdiff_t stack_diff = (buf - (char *)ptr); - stack_diff = stack_diff >= 0 ? stack_diff : -stack_diff; - if (stack_diff < (ptrdiff_t)stack_expand_limit) - stack_expand(ptr); + char volatile fill[PAGE_4K]; + char volatile *p; + + memset((void *)fill, (unsigned char)nr_calls, sizeof(fill)); + p = fill; + p[PAGE_4K / 2] = (unsigned char)nr_calls; + + if (nr_calls != 0) { + stack_expand(ret, nr_calls-1); + } else { + *ret = (unsigned long)&fill[0]; + } } static int test_stack_f(va_list ap) { - char s; - stack_expand(&s); + unsigned long ret = 0; + unsigned long ret_addr = (unsigned long)&ret; + + /* + * We can't just dirty the stack in precise + * way without using assembly. Thus lets do + * the following trick: + * - assume 8K will be enough to carry all + * arguments passed for all calls, still + * we might need to adjust this value + */ + stack_expand(&ret, (stack_expand_limit - 2 * page_size) / page_size); return 0; } @@ -193,6 +213,11 @@ main_f(va_list ap) int main() { + page_size = sysconf(_SC_PAGESIZE); + + /* Page should be at least 4K */ + assert(page_size >= PAGE_4K); + memory_init(); fiber_init(fiber_cxx_invoke); fiber_attr_create(&default_attr); -- 2.26.2
prev parent reply other threads:[~2020-10-15 16:28 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-10-15 14:28 Cyrill Gorcunov 2020-10-15 16:28 ` Cyrill Gorcunov [this message]
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20201015162807.GF173841@grain \ --to=gorcunov@gmail.com \ --cc=tarantool-patches@dev.tarantool.org \ --subject='Re: [Tarantool-patches] [PATCH] test/uint: fiber' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox