From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3CDBC02185 for ; Tue, 14 Jan 2025 18:13:54 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 49BEC28001C; Tue, 14 Jan 2025 13:13:54 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 44C15280006; Tue, 14 Jan 2025 13:13:54 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 315C428001C; Tue, 14 Jan 2025 13:13:54 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 137EE280006 for ; Tue, 14 Jan 2025 13:13:54 -0500 (EST) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id CD0EE160338 for ; Tue, 14 Jan 2025 18:13:53 +0000 (UTC) X-FDA: 83006855946.07.4C46BA5 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) by imf22.hostedemail.com (Postfix) with ESMTP id D15C5C0012 for ; Tue, 14 Jan 2025 18:13:51 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=s3TX6lvt; spf=pass (imf22.hostedemail.com: domain of shakeel.butt@linux.dev designates 91.218.175.188 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1736878432; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=vbLq7bgoJ4Eohsw7Izd1/q6MtF3gwn3as+coqDROMA4=; b=f9QDR4EoqqW31YvREk288ovlt6TQDuEpjc00GsPHcB7Z9orB7H5laK2iXRrgiMTWp9/VjT y5JgpitpGuJ8XhYA7KqxuDMYKqPdfnUXY5Uxca9QTgJK7AsOy3IVTNXt7vcxOpcBjfFkoc ZQ+QBnWhhtdfid0qpqrt+vMXzHkbja0= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1736878432; a=rsa-sha256; cv=none; b=Nd+wJkZmJtpvoziNKDmLVc3M96A4yI3NsmbEXyZKT86XJdhrpCLPw8woxuI01fc3sI+LDW 8GfogEuOADQeeX53vIMFGn3ClZH3Bl89ydhCSTkuKUezXnfoUpTb0w4b9HmA8WMU2FjSKU 5uUjWskz6V98p1byi5YXovHTEJF/5kw= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=s3TX6lvt; spf=pass (imf22.hostedemail.com: domain of shakeel.butt@linux.dev designates 91.218.175.188 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev Date: Tue, 14 Jan 2025 10:13:40 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1736878424; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=vbLq7bgoJ4Eohsw7Izd1/q6MtF3gwn3as+coqDROMA4=; b=s3TX6lvtRZERvGPYFIxS+ysEU3wtuzBBuuVfeTAQepjyryMCnKKmlx2/f3yT9K3B7jar9R yL7JHe9+842QPf7Kw5Jz0uqDaTBgPfucuVESjpCcVNzQT5cHhnhSz6m5T+9Ucax7leILFU nsbt4kV7NgaHlxaPfv1r2ISppx4ZkIE= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Shakeel Butt To: SeongJae Park , David Hildenbrand , Lorenzo Stoakes , Liam.Howlett@oracle.com, Vlastimil Babka Cc: Andrew Morton , Jens Axboe , Pavel Begunkov , damon@lists.linux.dev, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH] mm/madvise: remove redundant mmap_lock operations from process_madvise() Message-ID: References: <20250111004618.1566-1-sj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250111004618.1566-1-sj@kernel.org> X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: D15C5C0012 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: ydnz69o78axtxonentfox6r9sghu5ban X-HE-Tag: 1736878431-798423 X-HE-Meta: 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 /Im83LjS a60vWqCnwPGEFfPu/1jgWZ4J+AzVGPok8REvYTwZ5z7qr03CpyDfa5byUXpCE/1cqoCq49/B65aJklqjWn+PMAlsRKgjrNmivk2GMEAGK4nyHKZKoC5yeSHbty7rnhQFw8Co/UeojwogirQ6/M6w07fCxDdOSasLjDijFmoDL2GOKILnRQ+lF3n87/cwx+/NPuQl7eLz6lejzUWXozTPahfERlzEVHYXbkcfqSEZyRNGn+ffTKLemGpg0otFn2kTfxXBVsNregsOvEyNbW60yBH/OruvE8xU3xiSZAGPE98nX7wwQtWeeOQ26xRb2bAhfMoRM 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: Ccing relevant folks. On Fri, Jan 10, 2025 at 04:46:18PM -0800, SeongJae Park wrote: > process_madvise() calls do_madvise() for each address range. Then, each > do_madvise() invocation holds and releases same mmap_lock. Optimize the > redundant lock operations by doing the locking in process_madvise(), and > inform do_madvise() that the lock is already held and therefore can be > skipped. > > Evaluation > ========== > > I measured the time to apply MADV_DONTNEED advice to 256 MiB memory > using multiple madvise() calls, 4 KiB per each call. I also do the same > with process_madvise(), but with varying iovec size from 1 to 1024. > The source code for the measurement is available at GitHub[1]. > > The measurement results are as below. 'sz_batches' column shows the > iovec size of process_madvise() calls. '0' is for madvise() calls case. > 'before' and 'after' columns are the measured time to apply > MADV_DONTNEED to the 256 MiB memory buffer in nanoseconds, on kernels > that built without and with this patch, respectively. So lower value > means better efficiency. 'after/before' column is the ratio of 'after' > to 'before'. > > sz_batches before after after/before > 0 124062365 96670188 0.779206393494111 > 1 136341258 113915688 0.835518827323714 > 2 105314942 78898211 0.749164453796119 > 4 82012858 59778998 0.728897875989153 > 8 82562651 51003069 0.617749895167489 > 16 71474930 47575960 0.665631431888076 > 32 71391211 42902076 0.600943385033768 > 64 68225932 41337835 0.605896230190011 > 128 71053578 42467240 0.597679120395598 > 256 85094126 41630463 0.489228398679364 > 512 68531628 44049763 0.6427654542221 > 1024 79338892 43370866 0.546653285755491 > > The measurement shows this patch reduces the process_madvise() latency, > proportional to the batching size, from about 25% with the batch size 2 > to about 55% with the batch size 1,024. The trend is somewhat we can > expect. > > Interestingly, this patch has also optimize madvise() and single batch > size process_madvise(), though. I ran this test multiple times, but the > results are consistent. I'm still investigating if there are something > I'm missing. But I believe the investigation may not necessarily be a > blocker of this RFC, so just posting this. I will add updates of the > madvise() and single batch size process_madvise() investigation later. > > [1] https://github.com/sjp38/eval_proc_madvise > > Signed-off-by: SeongJae Park > --- > include/linux/mm.h | 3 ++- > io_uring/advise.c | 2 +- > mm/damon/vaddr.c | 2 +- > mm/madvise.c | 54 +++++++++++++++++++++++++++++++++++----------- > 4 files changed, 45 insertions(+), 16 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 612b513ebfbd..e3ca5967ebd4 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3459,7 +3459,8 @@ int do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, > unsigned long end, struct list_head *uf, bool unlock); > extern int do_munmap(struct mm_struct *, unsigned long, size_t, > struct list_head *uf); > -extern int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior); > +extern int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, > + int behavior, bool lock_held); > > #ifdef CONFIG_MMU > extern int __mm_populate(unsigned long addr, unsigned long len, > diff --git a/io_uring/advise.c b/io_uring/advise.c > index cb7b881665e5..010b55d5a26e 100644 > --- a/io_uring/advise.c > +++ b/io_uring/advise.c > @@ -56,7 +56,7 @@ int io_madvise(struct io_kiocb *req, unsigned int issue_flags) > > WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); > > - ret = do_madvise(current->mm, ma->addr, ma->len, ma->advice); > + ret = do_madvise(current->mm, ma->addr, ma->len, ma->advice, false); > io_req_set_res(req, ret, 0); > return IOU_OK; > #else > diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c > index a6174f725bd7..30b5a251d73e 100644 > --- a/mm/damon/vaddr.c > +++ b/mm/damon/vaddr.c > @@ -646,7 +646,7 @@ static unsigned long damos_madvise(struct damon_target *target, > if (!mm) > return 0; > > - applied = do_madvise(mm, start, len, behavior) ? 0 : len; > + applied = do_madvise(mm, start, len, behavior, false) ? 0 : len; > mmput(mm); > > return applied; > diff --git a/mm/madvise.c b/mm/madvise.c > index 49f3a75046f6..c107376db9d5 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -1637,7 +1637,8 @@ int madvise_set_anon_name(struct mm_struct *mm, unsigned long start, > * -EAGAIN - a kernel resource was temporarily unavailable. > * -EPERM - memory is sealed. > */ > -int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior) > +int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, > + int behavior, bool lock_held) > { > unsigned long end; > int error; > @@ -1668,12 +1669,14 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh > return madvise_inject_error(behavior, start, start + len_in); > #endif > > - write = madvise_need_mmap_write(behavior); > - if (write) { > - if (mmap_write_lock_killable(mm)) > - return -EINTR; > - } else { > - mmap_read_lock(mm); > + if (!lock_held) { > + write = madvise_need_mmap_write(behavior); > + if (write) { > + if (mmap_write_lock_killable(mm)) > + return -EINTR; > + } else { > + mmap_read_lock(mm); > + } > } > > start = untagged_addr_remote(mm, start); > @@ -1692,17 +1695,19 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh > } > blk_finish_plug(&plug); > > - if (write) > - mmap_write_unlock(mm); > - else > - mmap_read_unlock(mm); > + if (!lock_held) { > + if (write) > + mmap_write_unlock(mm); > + else > + mmap_read_unlock(mm); > + } > > return error; > } > > SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) > { > - return do_madvise(current->mm, start, len_in, behavior); > + return do_madvise(current->mm, start, len_in, behavior, false); > } > > /* Perform an madvise operation over a vector of addresses and lengths. */ > @@ -1711,12 +1716,28 @@ static ssize_t vector_madvise(struct mm_struct *mm, struct iov_iter *iter, > { > ssize_t ret = 0; > size_t total_len; > + bool hold_lock = true; > + int write; > > total_len = iov_iter_count(iter); > > +#ifdef CONFIG_MEMORY_FAILURE > + if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE) > + hold_lock = false; > +#endif > + if (hold_lock) { > + write = madvise_need_mmap_write(behavior); > + if (write) { > + if (mmap_write_lock_killable(mm)) > + return -EINTR; > + } else { > + mmap_read_lock(mm); > + } > + } > + > while (iov_iter_count(iter)) { > ret = do_madvise(mm, (unsigned long)iter_iov_addr(iter), > - iter_iov_len(iter), behavior); > + iter_iov_len(iter), behavior, hold_lock); > /* > * An madvise operation is attempting to restart the syscall, > * but we cannot proceed as it would not be correct to repeat > @@ -1739,6 +1760,13 @@ static ssize_t vector_madvise(struct mm_struct *mm, struct iov_iter *iter, > iov_iter_advance(iter, iter_iov_len(iter)); > } > > + if (hold_lock) { > + if (write) > + mmap_write_unlock(mm); > + else > + mmap_read_unlock(mm); > + } > + > ret = (total_len - iov_iter_count(iter)) ? : ret; > > return ret; > -- > 2.39.5