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Tue, 5 Dec 2023 13:01:35 -0500 (EST) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.9.0-alpha0-1178-geeaf0069a7-fm-20231114.001-geeaf0069 MIME-Version: 1.0 Message-Id: <8d8c22e2-1ca4-4400-a5e5-7745c298893a@app.fastmail.com> In-Reply-To: <20231205131608.GB55404@pevik> References: <20231204184817.3570465-1-shr@devkernel.io> <20231204184817.3570465-3-shr@devkernel.io> <20231205131608.GB55404@pevik> Date: Tue, 05 Dec 2023 10:01:09 -0800 From: "Stefan Roesch" To: "Petr Vorel" Cc: kernel-team@fb.com, david@redhat.com, oliver.sang@intel.com, linux-mm@kvack.org, ltp@lists.linux.it, liwang@redhat.com Subject: Re: [PATCH v3 2/2] add ksm test for smart-scan feature Content-Type: text/plain X-Rspamd-Queue-Id: 6F716180044 X-Rspam-User: X-Stat-Signature: askp9qfdpmes5bummmaatxrmio7h6h7r X-Rspamd-Server: rspam01 X-HE-Tag: 1701799300-896855 X-HE-Meta: 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 91nFsUHE KsIQzfEwpm8qFfiqzsTRvIg8Mxc8P82g4f6u823vhoJ009+Eg9K3hbKnQ2ebYpK/lFAtMmmgyvBn7rydfnmAxRxQG7KT/Ei7Bbiu2I2KJV5NCgM4GFcXVHF39y8B8/V6M1OSCQZI4rL1+Z7Rv++8CvdkXrmarCNDW/HDp X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Dec 5, 2023, at 5:16 AM, Petr Vorel wrote: > Hi Stefan, > >> This adds a new ksm (kernel samepage merging) test to evaluate the new >> smart scan feature. It allocates a page and fills it with 'a' >> characters. It captures the pages_skipped counter, waits for a few >> iterations and captures the pages_skipped counter again. The expectation >> is that over 50% of the page scans are skipped (There is only one page >> that has KSM enabled and it gets scanned during each iteration and it >> cannot be de-duplicated). > >> Signed-off-by: Stefan Roesch >> --- >> runtest/mm | 1 + >> testcases/kernel/mem/.gitignore | 1 + >> testcases/kernel/mem/ksm/ksm07.c | 131 +++++++++++++++++++++++++++++++ >> 3 files changed, 133 insertions(+) >> create mode 100644 testcases/kernel/mem/ksm/ksm07.c > >> diff --git a/runtest/mm b/runtest/mm >> index f288fed36..d859b331c 100644 >> --- a/runtest/mm >> +++ b/runtest/mm >> @@ -70,6 +70,7 @@ ksm05 ksm05 -I 10 >> ksm06 ksm06 >> ksm06_1 ksm06 -n 10 >> ksm06_2 ksm06 -n 8000 >> +ksm07 ksm07 > >> cpuset01 cpuset01 > >> diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore >> index 7258489ed..c96fe8bfc 100644 >> --- a/testcases/kernel/mem/.gitignore >> +++ b/testcases/kernel/mem/.gitignore >> @@ -53,6 +53,7 @@ >> /ksm/ksm04 >> /ksm/ksm05 >> /ksm/ksm06 >> +/ksm/ksm07 >> /mem/mem02 >> /mmapstress/mmap-corruption01 >> /mmapstress/mmapstress01 >> diff --git a/testcases/kernel/mem/ksm/ksm07.c b/testcases/kernel/mem/ksm/ksm07.c >> new file mode 100644 >> index 000000000..16153fdb2 >> --- /dev/null >> +++ b/testcases/kernel/mem/ksm/ksm07.c >> @@ -0,0 +1,131 @@ >> +// SPDX-License-Identifier: GPL-2.0-or-later >> +/* >> + * Copyright (C) 2010-2017 Red Hat, Inc. >> + */ >> +/*\ >> + * [Description] >> + * >> + * Kernel Samepage Merging (KSM) >> + * >> + * This adds a new ksm (kernel samepage merging) test to evaluate the new >> + * smart scan feature. It allocates a page and fills it with 'a' >> + * characters. It captures the pages_skipped counter, waits for a few >> + * iterations and captures the pages_skipped counter again. The expectation >> + * is that over 50% of the page scans are skipped (There is only one page >> + * that has KSM enabled and it gets scanned during each iteration and it >> + * cannot be de-duplicated). >> + * >> + * Prerequisites: >> + * >> + * 1) ksm and ksmtuned daemons need to be disabled. Otherwise, it could >> + * distrub the testing as they also change some ksm tunables depends >> + * on current workloads. >> + */ >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include "../include/mem.h" >> +#include "ksm_common.h" >> + >> +/* This test allocates one page, fills the page with a's, captures the >> + * full_scan and pages_skipped counters. Then it makes sure at least 3 >> + * full scans have been performed and measures the above counters again. >> + * The expectation is that at least 50% of the pages are skipped. >> + * >> + * To wait for at least 3 scans it uses the wait_ksmd_full_scan() function. In >> + * reality, it will be a lot more scans as the wait_ksmd_full_scan() function >> + * sleeps for one second. >> + */ >> +static void create_memory(void) >> +{ >> + int status; >> + int full_scans_begin; >> + int full_scans_end; >> + int pages_skipped_begin; >> + int pages_skipped_end; >> + int diff_pages; >> + int diff_scans; >> + unsigned long page_size; >> + char *memory; >> + >> + /* Apply for the space for memory. */ >> + page_size = sysconf(_SC_PAGE_SIZE); >> + memory = SAFE_MALLOC(page_size); >> + >> + for (int i = 0; i < 1; i++) { >> + memory = SAFE_MMAP(NULL, page_size, PROT_READ|PROT_WRITE, >> + MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); >> +#ifdef HAVE_DECL_MADV_MERGEABLE >> + if (madvise(memory, page_size, MADV_MERGEABLE) == -1) >> + tst_brk(TBROK|TERRNO, "madvise"); >> +#endif >> + } >> + memset(memory, 'a', page_size); >> + >> + tst_res(TINFO, "KSM merging..."); >> + if (access(PATH_KSM "max_page_sharing", F_OK) == 0) { >> + SAFE_FILE_PRINTF(PATH_KSM "run", "2"); >> + } >> + >> + /* Set defalut ksm scan values. */ >> + SAFE_FILE_PRINTF(PATH_KSM "run", "1"); >> + SAFE_FILE_PRINTF(PATH_KSM "pages_to_scan", "%ld", 100l); >> + SAFE_FILE_PRINTF(PATH_KSM "sleep_millisecs", "0"); >> + >> + /* Measure pages skipped aka "smart scan". */ >> + SAFE_FILE_SCANF(PATH_KSM "full_scans", "%d", &full_scans_begin); >> + SAFE_FILE_SCANF(PATH_KSM "pages_skipped", "%d", &pages_skipped_begin); > Unfortunately SAFE_FILE_SCANF quits on missing file and > /sys/kernel/mm/ksm/pages_skipped is not on kernel < 6.7. > > safe_file_vprintf() which SAFE_FILE_SCANF() internally uses does not support any > flag to quit with TCONF instead TBROK when /sys/kernel/mm/ksm/pages_skipped does > not exists. > > We could use access() in setup function, but another line in .save_restore will > help: > > {PATH_KSM "pages_skipped", NULL, TST_SR_TCONF} > I don't think this works correctly. I see a warning: tst_sys_conf.c:144: TINFO: Failed to open FILE '/sys/kernel/mm/ksm/pages_skipped' The difference to the other ksm files is, that this is not writeable. >> + wait_ksmd_full_scan(); >> + >> + tst_res(TINFO, "stop KSM."); >> + SAFE_FILE_PRINTF(PATH_KSM "run", "0"); >> + >> + SAFE_FILE_SCANF(PATH_KSM "full_scans", "%d", &full_scans_end); >> + SAFE_FILE_SCANF(PATH_KSM "pages_skipped", "%d", &pages_skipped_end); >> + diff_pages = pages_skipped_end - pages_skipped_begin; >> + diff_scans = full_scans_end - full_scans_begin; > > I was going to merge this (with minor cleanup), but the only remaining issue is > that we allow to test run repeatedly via -iN: > > # ./ksm07 -i2 > tst_test.c:1574: TINFO: Timeout per run is 0h 00m 30s > ksm07.c:73: TINFO: KSM merging... > ksm_helper.c:36: TINFO: ksm daemon takes 1s to run two full scans > ksm07.c:88: TINFO: stop KSM. > ksm07.c:99: TPASS: smart_scan skipped more than 50% of the pages. > ksm07.c:73: TINFO: KSM merging... > ksm_helper.c:36: TINFO: ksm daemon takes 1s to run two full scans > ksm07.c:88: TINFO: stop KSM. > ksm07.c:97: TFAIL: not enough pages have been skipped by smart_scan. > > I'm confused, how to reset KSM to be able to run the test more times? > >> + >> + if (diff_pages < diff_scans * 50 / 100) { >> + tst_res(TFAIL, "not enough pages have been skipped by smart_scan."); >> + } else { >> + tst_res(TPASS, "smart_scan skipped more than 50%% of the pages."); >> + } >> + >> + while (waitpid(-1, &status, 0) > 0) >> + if (WEXITSTATUS(status) != 0) >> + tst_res(TFAIL, "child exit status is %d", >> + WEXITSTATUS(status)); >> +} > This is not needed, done by check_child_status() in > lib/tst_test.c. > >> + >> +static void verify_ksm(void) >> +{ >> + create_memory(); >> +} > Why this wrapper? "verify_" as a pattern name is not a must. >> + >> +static struct tst_test test = { >> + .needs_root = 1, >> + .forks_child = 1, >> + .options = (struct tst_option[]) { >> + {} >> + }, >> + .save_restore = (const struct tst_path_val[]) { >> + {"/sys/kernel/mm/ksm/run", NULL, TST_SR_TCONF}, >> + {"/sys/kernel/mm/ksm/sleep_millisecs", NULL, TST_SR_TCONF}, >> + {"/sys/kernel/mm/ksm/smart_scan", "1", > We have PATH_KSM definition, lets use it. > >> + TST_SR_SKIP_MISSING | TST_SR_TCONF}, >> + {} >> + }, >> + .needs_kconfigs = (const char *const[]){ >> + "CONFIG_KSM=y", >> + NULL >> + }, >> + .test_all = verify_ksm, >> +}; > > I was going to merge your patch with following changes. > We just need solve -i2 issue. > I have a solution for this: we need another madvise call at the end. I'll send it with the next version. > Kind regards, > Petr > > diff --git testcases/kernel/mem/ksm/ksm07.c testcases/kernel/mem/ksm/ksm07.c > index 16153fdb2..e5c31775b 100644 > --- testcases/kernel/mem/ksm/ksm07.c > +++ testcases/kernel/mem/ksm/ksm07.c > @@ -5,35 +5,25 @@ > /*\ > * [Description] > * > - * Kernel Samepage Merging (KSM) > + * Kernel Samepage Merging (KSM) for smart scan feature > * > - * This adds a new ksm (kernel samepage merging) test to evaluate the new > - * smart scan feature. It allocates a page and fills it with 'a' > - * characters. It captures the pages_skipped counter, waits for a few > - * iterations and captures the pages_skipped counter again. The expectation > - * is that over 50% of the page scans are skipped (There is only one page > - * that has KSM enabled and it gets scanned during each iteration and it > - * cannot be de-duplicated). > + * Test allocates a page and fills it with 'a' characters. It captures the > + * pages_skipped counter, waits for a few iterations and captures the > + * pages_skipped counter again. The expectation is that over 50% of the page > + * scans are skipped. (There is only one page that has KSM enabled and it gets > + * scanned during each iteration and it cannot be de-duplicated.) > * > - * Prerequisites: > + * Smart scan feature was added in kernel v6.7. > * > - * 1) ksm and ksmtuned daemons need to be disabled. Otherwise, it could > - * distrub the testing as they also change some ksm tunables depends > - * on current workloads. > + * [Prerequisites] > + * > + * ksm and ksmtuned daemons need to be disabled. Otherwise, it could > + * distrub the testing as they also change some ksm tunables depends > + * on current workloads. > */ > -#include > -#include > -#include > + > #include > -#include > -#include > -#include > -#include > -#include > -#include > -#include > -#include "../include/mem.h" > -#include "ksm_common.h" > +#include "mem.h" > > /* This test allocates one page, fills the page with a's, captures the > * full_scan and pages_skipped counters. Then it makes sure at least 3 > @@ -46,7 +36,6 @@ > */ > static void create_memory(void) > { > - int status; > int full_scans_begin; > int full_scans_end; > int pages_skipped_begin; > @@ -70,10 +59,10 @@ static void create_memory(void) > } > memset(memory, 'a', page_size); > > - tst_res(TINFO, "KSM merging..."); > - if (access(PATH_KSM "max_page_sharing", F_OK) == 0) { > + tst_res(TINFO, "KSM merging"); > + > + if (access(PATH_KSM "max_page_sharing", F_OK) == 0) > SAFE_FILE_PRINTF(PATH_KSM "run", "2"); > - } > > /* Set defalut ksm scan values. */ > SAFE_FILE_PRINTF(PATH_KSM "run", "1"); > @@ -85,7 +74,7 @@ static void create_memory(void) > SAFE_FILE_SCANF(PATH_KSM "pages_skipped", "%d", &pages_skipped_begin); > wait_ksmd_full_scan(); > > - tst_res(TINFO, "stop KSM."); > + tst_res(TINFO, "stop KSM"); > SAFE_FILE_PRINTF(PATH_KSM "run", "0"); > > SAFE_FILE_SCANF(PATH_KSM "full_scans", "%d", &full_scans_end); > @@ -93,21 +82,10 @@ static void create_memory(void) > diff_pages = pages_skipped_end - pages_skipped_begin; > diff_scans = full_scans_end - full_scans_begin; > > - if (diff_pages < diff_scans * 50 / 100) { > - tst_res(TFAIL, "not enough pages have been skipped by smart_scan."); > - } else { > - tst_res(TPASS, "smart_scan skipped more than 50%% of the pages."); > - } > - > - while (waitpid(-1, &status, 0) > 0) > - if (WEXITSTATUS(status) != 0) > - tst_res(TFAIL, "child exit status is %d", > - WEXITSTATUS(status)); > -} > - > -static void verify_ksm(void) > -{ > - create_memory(); > + if (diff_pages < diff_scans * 50 / 100) > + tst_res(TFAIL, "not enough pages have been skipped by smart_scan"); > + else > + tst_res(TPASS, "smart_scan skipped more than 50%% of the pages"); > } > > static struct tst_test test = { > @@ -117,9 +95,10 @@ static struct tst_test test = { > {} > }, > .save_restore = (const struct tst_path_val[]) { > - {"/sys/kernel/mm/ksm/run", NULL, TST_SR_TCONF}, > - {"/sys/kernel/mm/ksm/sleep_millisecs", NULL, TST_SR_TCONF}, > - {"/sys/kernel/mm/ksm/smart_scan", "1", > + {PATH_KSM "pages_skipped", NULL, TST_SR_TCONF}, > + {PATH_KSM "run", NULL, TST_SR_TCONF}, > + {PATH_KSM "sleep_millisecs", NULL, TST_SR_TCONF}, > + {PATH_KSM "smart_scan", "1", > TST_SR_SKIP_MISSING | TST_SR_TCONF}, > {} > }, > @@ -127,5 +106,5 @@ static struct tst_test test = { > "CONFIG_KSM=y", > NULL > }, > - .test_all = verify_ksm, > + .test_all = create_memory, > };