public inbox for gdb-cvs@sourceware.org help / color / mirror / Atom feed
From: Tom Tromey <tromey@sourceware.org> To: gdb-cvs@sourceware.org Subject: [binutils-gdb] "Finalize" the DWARF index in the background Date: Tue, 12 Apr 2022 15:41:11 +0000 (GMT) [thread overview] Message-ID: <20220412154111.EECFE3858C54@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=7e752790937c73d8ca61dc207f8e1e609d5644c0 commit 7e752790937c73d8ca61dc207f8e1e609d5644c0 Author: Tom Tromey <tom@tromey.com> Date: Sat May 22 15:20:06 2021 -0600 "Finalize" the DWARF index in the background After scanning the CUs, the DWARF indexer merges all the data into a single vector, canonicalizing C++ names as it proceeds. While not necessarily single-threaded, this process is currently done in just one thread, to keep memory costs lower. However, this work is all done without reference to any data outside of the indexes. This patch improves the apparent performance of GDB by moving it to the background. All uses of the index are then made to wait for this process to complete. In our ongoing example, this reduces the scanning time on gdb itself to 0.173937 (wall). Recall that before this patch, the time was 0.668923; and psymbol reader does this in 1.598869. That is, at the end of this series, we see about a 10x speedup. Diff: --- gdb/dwarf2/cooked-index.c | 10 ++++++++-- gdb/dwarf2/cooked-index.h | 17 +++++++++++++++++ 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/gdb/dwarf2/cooked-index.c b/gdb/dwarf2/cooked-index.c index e56a47520f8..784c06ea04b 100644 --- a/gdb/dwarf2/cooked-index.c +++ b/gdb/dwarf2/cooked-index.c @@ -114,9 +114,13 @@ cooked_index::add (sect_offset die_offset, enum dwarf_tag tag, } cooked_index_vector::cooked_index_vector (vec_type &&vec) - : m_vector (std::move (vec)) + : m_vector (std::move (vec)), + m_future (gdb::thread_pool::g_thread_pool->post_task + ([this] () + { + finalize (); + })) { - finalize (); } /* See cooked-index.h. */ @@ -149,6 +153,8 @@ cooked_index_vector::get_addrmaps () cooked_index_vector::range cooked_index_vector::find (gdb::string_view name, bool completing) { + m_future.wait (); + auto lower = std::lower_bound (m_entries.begin (), m_entries.end (), name, [=] (const cooked_index_entry *entry, diff --git a/gdb/dwarf2/cooked-index.h b/gdb/dwarf2/cooked-index.h index 188155190ec..661664d9f84 100644 --- a/gdb/dwarf2/cooked-index.h +++ b/gdb/dwarf2/cooked-index.h @@ -254,6 +254,17 @@ public: explicit cooked_index_vector (vec_type &&vec); DISABLE_COPY_AND_ASSIGN (cooked_index_vector); + ~cooked_index_vector () + { + /* The 'finalize' method may be run in a different thread. If + this object is destroyed before this completes, then the method + will end up writing to freed memory. Waiting for this to + complete avoids this problem; and the cost seems ignorable + because creating and immediately destroying the debug info is a + relatively rare thing to do. */ + m_future.wait (); + } + /* A simple range over part of m_entries. */ typedef iterator_range<std::vector<cooked_index_entry *>::iterator> range; @@ -265,6 +276,7 @@ public: /* Return a range of all the entries. */ range all_entries () { + m_future.wait (); return { m_entries.begin (), m_entries.end () }; } @@ -305,6 +317,11 @@ private: /* Storage for canonical names. */ std::vector<gdb::unique_xmalloc_ptr<char>> m_names; + + /* A future that tracks when the 'finalize' method is done. Note + that the 'get' method is never called on this future, only + 'wait'. */ + std::future<void> m_future; }; #endif /* GDB_DWARF2_COOKED_INDEX_H */
reply other threads:[~2022-04-12 15:41 UTC|newest] Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=20220412154111.EECFE3858C54@sourceware.org \ --to=tromey@sourceware.org \ --cc=gdb-cvs@sourceware.org \ /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: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).