From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: + hugetlb-support-file_region-coalescing-again.patch added to -mm tree Date: Tue, 11 Feb 2020 15:19:27 -0800 Message-ID: <20200211231927.uRHBj9LPL%akpm@linux-foundation.org> References: <20200203173311.6269a8be06a05e5a4aa08a93@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:45202 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727905AbgBKXTa (ORCPT ); Tue, 11 Feb 2020 18:19:30 -0500 In-Reply-To: <20200203173311.6269a8be06a05e5a4aa08a93@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: almasrymina@google.com, gthelen@google.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, rientjes@google.com, sandipan@linux.ibm.com, shakeelb@google.com, shuah@kernel.org The patch titled Subject: hugetlb: support file_region coalescing again has been added to the -mm tree. Its filename is hugetlb-support-file_region-coalescing-again.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/hugetlb-support-file_region-coalescing-again.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/hugetlb-support-file_region-coalescing-again.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Mina Almasry Subject: hugetlb: support file_region coalescing again An earlier patch in this series disabled file_region coalescing in order to hang the hugetlb_cgroup uncharge info on the file_region entries. This patch re-adds support for coalescing of file_region entries. Essentially everytime we add an entry, we call a recursive function that tries to coalesce the added region with the regions next to it. The worst case call depth for this function is 3: one to coalesce with the region next to it, one to coalesce to the region prev, and one to reach the base case. This is an important performance optimization as private mappings add their entries page by page, and we could incur big performance costs for large mappings with lots of file_region entries in their resv_map. Link: http://lkml.kernel.org/r/20200211213128.73302-7-almasrymina@google.com Signed-off-by: Mina Almasry Cc: David Rientjes Cc: Greg Thelen Cc: Mike Kravetz Cc: Sandipan Das Cc: Shakeel Butt Cc: Shuah Khan Signed-off-by: Andrew Morton --- mm/hugetlb.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) --- a/mm/hugetlb.c~hugetlb-support-file_region-coalescing-again +++ a/mm/hugetlb.c @@ -276,6 +276,86 @@ static void record_hugetlb_cgroup_unchar #endif } +static bool has_same_uncharge_info(struct file_region *rg, + struct file_region *org) +{ +#ifdef CONFIG_CGROUP_HUGETLB + return rg && org && + rg->reservation_counter == org->reservation_counter && + rg->css == org->css; + +#else + return true; +#endif +} + +#ifdef CONFIG_DEBUG_VM +static void dump_resv_map(struct resv_map *resv) +{ + struct list_head *head = &resv->regions; + struct file_region *rg = NULL; + + pr_err("--------- start print resv_map ---------\n"); + list_for_each_entry(rg, head, link) { + pr_err("rg->from=%ld, rg->to=%ld, rg->reservation_counter=%px, rg->css=%px\n", + rg->from, rg->to, rg->reservation_counter, rg->css); + } + pr_err("--------- end print resv_map ---------\n"); +} + +/* Debug function to loop over the resv_map and make sure that coalescing is + * working. + */ +static void check_coalesce_bug(struct resv_map *resv) +{ + struct list_head *head = &resv->regions; + struct file_region *rg = NULL, *nrg = NULL; + + list_for_each_entry(rg, head, link) { + nrg = list_next_entry(rg, link); + + if (&nrg->link == head) + break; + + if (nrg->reservation_counter && nrg->from == rg->to && + nrg->reservation_counter == rg->reservation_counter && + nrg->css == rg->css) { + dump_resv_map(resv); + VM_BUG_ON(true); + } + } +} +#endif + +static void coalesce_file_region(struct resv_map *resv, struct file_region *rg) +{ + struct file_region *nrg = NULL, *prg = NULL; + + prg = list_prev_entry(rg, link); + if (&prg->link != &resv->regions && prg->to == rg->from && + has_same_uncharge_info(prg, rg)) { + prg->to = rg->to; + + list_del(&rg->link); + kfree(rg); + + coalesce_file_region(resv, prg); + return; + } + + nrg = list_next_entry(rg, link); + if (&nrg->link != &resv->regions && nrg->from == rg->to && + has_same_uncharge_info(nrg, rg)) { + nrg->from = rg->from; + + list_del(&rg->link); + kfree(rg); + + coalesce_file_region(resv, nrg); + return; + } +} + /* Must be called with resv->lock held. Calling this with count_only == true * will count the number of pages to be added but will not modify the linked * list. If regions_needed != NULL and count_only == true, then regions_needed @@ -327,6 +407,7 @@ static long add_reservation_in_range(str record_hugetlb_cgroup_uncharge_info(h_cg, h, resv, nrg); list_add(&nrg->link, rg->link.prev); + coalesce_file_region(resv, nrg); } else if (regions_needed) *regions_needed += 1; } @@ -344,11 +425,15 @@ static long add_reservation_in_range(str resv, last_accounted_offset, t); record_hugetlb_cgroup_uncharge_info(h_cg, h, resv, nrg); list_add(&nrg->link, rg->link.prev); + coalesce_file_region(resv, nrg); } else if (regions_needed) *regions_needed += 1; } VM_BUG_ON(add < 0); +#ifdef CONFIG_DEBUG_VM + check_coalesce_bug(resv); +#endif return add; } _ Patches currently in -mm which might be from almasrymina@google.com are hugetlb_cgroup-add-hugetlb_cgroup-reservation-counter.patch hugetlb_cgroup-add-interface-for-charge-uncharge-hugetlb-reservations.patch hugetlb_cgroup-add-reservation-accounting-for-private-mappings.patch hugetlb-disable-region_add-file_region-coalescing.patch hugetlb_cgroup-add-accounting-for-shared-mappings.patch hugetlb_cgroup-support-noreserve-mappings.patch hugetlb-support-file_region-coalescing-again.patch hugetlb_cgroup-add-hugetlb_cgroup-reservation-tests.patch hugetlb_cgroup-add-hugetlb_cgroup-reservation-docs.patch