<html> <head> <style></style></head> <body class='hmmessage'><div dir='ltr'>Thanks for the explantion/comments. The increase in the TCACHE_NSLOTS_SMALL_MAX (which undercovers is limited to 1002 and 504 as you say) does help quit a bit in this case as I ran some profiles:<br><br>default setting ==><br>Excl. Incl. Name<br>User CPU User CPU<br> sec. sec.<br> 390.275 481.712 jepvt_arena_dalloc_bin_locked<br> 217.540 769.057 je_free<br> 201.956 488.113 jepvt_arena_tcache_fill_small<br> 199.592 283.012 arena_bin_malloc_hard<br> 75.292 712.736 je_malloc<br><br>callee for je_free (most of runtime if in jepvt_tcache_bin_flush_small) <br>217.540 *je_free<br>551.517 jepvt_tcache_bin_flush_small<br><br>new setting ==><br>Excl. Incl. Name<br>User CPU User CPU<br> sec. sec.<br> 234.378 234.730 je_free<br> 154.511 307.229 jepvt_arena_malloc<br> 78.713 385.964 je_malloc<br> 57.772 70.838 jepvt_arena_dalloc_bin_locked<br><br>callee info for jepvt_arena_malloc:<br>Attr. Name<br>User CPU<br> sec.<br>154.511 *jepvt_arena_malloc<br> 82.232 jepvt_tcache_event_hard<br> 70.486 jepvt_tcache_alloc_small_hard<br><br><br>So we get quite a bit of runtime improvement -- but for our case the runtime in je_malloc and je_free is still quite high. Given above profile do you think modifying bin_info_run_size_calc() to use a larger initial min_run_size help? <br><br>thanks a lot,<br>--rajat <br><br><br><div><div id="SkyDrivePlaceholder"></div><hr id="stopSpelling">Subject: Re: jemalloc performance for very small allocations<br>From: jasone@canonware.com<br>Date: Tue, 30 Apr 2013 22:52:24 -0700<br>CC: jemalloc-discuss@canonware.com<br>To: garg_rajat@hotmail.com<br><br><div><div>On Apr 26, 2013, at 9:39 AM, Rajat Garg <<a href="mailto:garg_rajat@hotmail.com">garg_rajat@hotmail.com</a>> wrote:</div><blockquote><div class="ecxhmmessage" style="font-size:12pt;font-family:Calibri;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;orphans:2;text-align:-webkit-auto;text-indent:0px;text-transform:none;white-space:normal;widows:2;word-spacing:0px;"><div dir="ltr"><div dir="ltr"> I am using jemalloc 3.1.0, compiled with gcc 4.1.2 on CentOS release 5.6 for a compute intensive multithreaded application where bulk of allocations falls in 8-byte, 16-byte (stats below). We are seeing very high runtime in tcache_alloc_small_hard(), arena_tcache_fill_small() and arena_bin_malloc_hard(). The 8 and 16 bytes allocations happen in very large number. We probably want the allocations to come form tcache_alloc_easy() to not hit the locks and take less runtime. The allocations are mostly temporary in nature -- especially 8-byte ones -- so some number of 8-byte allocations are done, then they are freed and then alloc/free process repeated.<span class="ecxApple-converted-space"> </span><br><br>The runs use 8 threads (so 48 arenas and all other jemalloc settings are default) and are on an Intel Xeon server with 12-cores (no hyperthreading and no other user so no contention with other user; the peak memory in application is ~6.5GB and server has 128GB memory so no memory shortage/swapping etc.); the jemalloc output at the end of run is given below. As we can see, pretty much 8 and 16 byte bins are overloaded.</div></div></div></blockquote><div><br></div>Only 8 of the 48 arenas are being used in your test case. That said, the extra 40 are lazily initialized, so there's no need to change settings.</div><div><br><blockquote><div class="ecxhmmessage" style="font-size:12pt;font-family:Calibri;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;orphans:2;text-align:-webkit-auto;text-indent:0px;text-transform:none;white-space:normal;widows:2;word-spacing:0px;"><div dir="ltr"><div dir="ltr">A run with TCACHE_NSLOTS_SMALL_MAX=10000, LG_TCACHE_MAXCLASS_DEFAULT=10, changing small bins to hold only upto 224 bytes (NBINS=15), and hardcoding<span class="ecxApple-converted-space"> </span><br>tcache_bin_info[i].ncached_max = TCACHE_NSLOTS_SMALL_MAX in tcache.c file improves runtime by about 16% (for overall application runtime) but increases peak memory from 6.5GB to 6.7GB. We want the runtime to at least improve by another 10% without preferably any increase in peak memory (so even 6.5GB to 6.7GB is not desirable).<span class="ecxApple-converted-space"> </span><br>Any suggestions on what changes to jemalloc settings to try?<br></div></div></div></blockquote><br></div><div>I don't think the TCACHE_NSLOTS_SMALL_MAX setting is having as much effect for your test case as you might expect. Even with the setting of 10000, tcache is limited to 1002 and 504 regions for 8- and 16-byte regions, respectively. If you want to further increase the tcache region count, you will need to either increase the logical page size, or modify bin_info_run_size_calc() to use a larger initial min_run_size.</div><br><div>Jason</div></div> </div></body> </html>