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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AFC50ECAAD5 for ; Tue, 6 Sep 2022 15:27:59 +0000 (UTC) Received: from localhost ([::1]:45212 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oVaUY-0002ze-Pe for qemu-devel@archiver.kernel.org; Tue, 06 Sep 2022 11:27:58 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57216) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oVaQV-0007ZJ-6e for qemu-devel@nongnu.org; Tue, 06 Sep 2022 11:23:47 -0400 Received: from us-smtp-delivery-44.mimecast.com ([205.139.111.44]:48739) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oVaQS-0005J0-7z for qemu-devel@nongnu.org; Tue, 06 Sep 2022 11:23:46 -0400 Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-336-5Aq_gheiPIKcTwEZxs6hFw-1; Tue, 06 Sep 2022 11:23:32 -0400 X-MC-Unique: 5Aq_gheiPIKcTwEZxs6hFw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E4486101E167; Tue, 6 Sep 2022 15:23:31 +0000 (UTC) Received: from bahia (unknown [10.39.193.62]) by smtp.corp.redhat.com (Postfix) with ESMTP id CD869C15BB3; Tue, 6 Sep 2022 15:23:30 +0000 (UTC) Date: Tue, 6 Sep 2022 17:23:28 +0200 From: Greg Kurz To: Linus Heckemann Cc: qemu-devel@nongnu.org, Christian Schoenebeck , Philippe =?UTF-8?B?TWF0aGlldS1EYXVkw6k=?= , "Daniel P . =?UTF-8?B?QmVycmFuZ8Op?=" Subject: Re: [PATCH] 9pfs: use GHashTable for fid table Message-ID: <20220906172328.009be444@bahia> In-Reply-To: <20220905150300.3794196-1-git@sphalerite.org> References: <20220903150327.2780127-1-git@sphalerite.org> <20220905150300.3794196-1-git@sphalerite.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 Received-SPF: softfail client-ip=205.139.111.44; envelope-from=groug@kaod.org; helo=us-smtp-delivery-44.mimecast.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_SOFTFAIL=0.665, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Linus, Some more comments below. On Mon, 5 Sep 2022 17:03:00 +0200 Linus Heckemann wrote: > The previous implementation would iterate over the fid table for > lookup operations, resulting in an operation with O(n) complexity on > the number of open files and poor cache locality -- for every open, > stat, read, write, etc operation. > > This change uses a hashtable for this instead, significantly improving > the performance of the 9p filesystem. The runtime of NixOS's simple > installer test, which copies ~122k files totalling ~1.8GiB from 9p, > decreased by a factor of about 10. > > Signed-off-by: Linus Heckemann > --- > hw/9pfs/9p.c | 130 +++++++++++++++++++++++++++------------------------ > hw/9pfs/9p.h | 2 +- > 2 files changed, 69 insertions(+), 63 deletions(-) > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > index aebadeaa03..fb4b7fe852 100644 > --- a/hw/9pfs/9p.c > +++ b/hw/9pfs/9p.c > @@ -282,33 +282,31 @@ static V9fsFidState *coroutine_fn get_fid(V9fsPDU *pdu, int32_t fid) > V9fsFidState *f; > V9fsState *s = pdu->s; > > - QSIMPLEQ_FOREACH(f, &s->fid_list, next) { > - BUG_ON(f->clunked); > - if (f->fid == fid) { > - /* > - * Update the fid ref upfront so that > - * we don't get reclaimed when we yield > - * in open later. > - */ > - f->ref++; > - /* > - * check whether we need to reopen the > - * file. We might have closed the fd > - * while trying to free up some file > - * descriptors. > - */ > - err = v9fs_reopen_fid(pdu, f); > - if (err < 0) { > - f->ref--; > - return NULL; > - } > - /* > - * Mark the fid as referenced so that the LRU > - * reclaim won't close the file descriptor > - */ > - f->flags |= FID_REFERENCED; > - return f; > + f = g_hash_table_lookup(s->fids, GINT_TO_POINTER(fid)); > + if (f) { > + /* > + * Update the fid ref upfront so that > + * we don't get reclaimed when we yield > + * in open later. > + */ > + f->ref++; > + /* > + * check whether we need to reopen the > + * file. We might have closed the fd > + * while trying to free up some file > + * descriptors. > + */ > + err = v9fs_reopen_fid(pdu, f); > + if (err < 0) { > + f->ref--; > + return NULL; > } > + /* > + * Mark the fid as referenced so that the LRU > + * reclaim won't close the file descriptor > + */ > + f->flags |= FID_REFERENCED; > + return f; > } > return NULL; > } > @@ -317,12 +315,9 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid) > { > V9fsFidState *f; > > - QSIMPLEQ_FOREACH(f, &s->fid_list, next) { > + if (g_hash_table_contains(s->fids, GINT_TO_POINTER(fid))) { > /* If fid is already there return NULL */ > - BUG_ON(f->clunked); > - if (f->fid == fid) { > - return NULL; > - } > + return NULL; > } > f = g_new0(V9fsFidState, 1); > f->fid = fid; > @@ -333,7 +328,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid) > * reclaim won't close the file descriptor > */ > f->flags |= FID_REFERENCED; > - QSIMPLEQ_INSERT_TAIL(&s->fid_list, f, next); > + g_hash_table_insert(s->fids, GINT_TO_POINTER(fid), f); > > v9fs_readdir_init(s->proto_version, &f->fs.dir); > v9fs_readdir_init(s->proto_version, &f->fs_reclaim.dir); > @@ -424,12 +419,10 @@ static V9fsFidState *clunk_fid(V9fsState *s, int32_t fid) > { > V9fsFidState *fidp; > > - QSIMPLEQ_FOREACH(fidp, &s->fid_list, next) { > - if (fidp->fid == fid) { > - QSIMPLEQ_REMOVE(&s->fid_list, fidp, V9fsFidState, next); > - fidp->clunked = true; > - return fidp; > - } > + if (g_hash_table_steal_extended(s->fids, GINT_TO_POINTER(fid), > + NULL, (gpointer *) &fidp)) { > + fidp->clunked = true; > + return fidp; > } > return NULL; > } > @@ -439,10 +432,15 @@ void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu) > int reclaim_count = 0; > V9fsState *s = pdu->s; > V9fsFidState *f; > + GHashTableIter iter; > + gpointer fid; > + > + g_hash_table_iter_init(&iter, s->fids); > + > QSLIST_HEAD(, V9fsFidState) reclaim_list = > QSLIST_HEAD_INITIALIZER(reclaim_list); > > - QSIMPLEQ_FOREACH(f, &s->fid_list, next) { > + while (g_hash_table_iter_next(&iter, &fid, (gpointer *) &f)) { > /* > * Unlink fids cannot be reclaimed. Check > * for them and skip them. Also skip fids > @@ -518,12 +516,11 @@ static int coroutine_fn v9fs_mark_fids_unreclaim(V9fsPDU *pdu, V9fsPath *path) > { > int err; > V9fsState *s = pdu->s; > - V9fsFidState *fidp, *fidp_next; > + V9fsFidState *fidp; > + gpointer fid; > + GHashTableIter iter; > > - fidp = QSIMPLEQ_FIRST(&s->fid_list); > - if (!fidp) { > - return 0; > - } > + g_hash_table_iter_init(&iter, s->fids); > Using this external iterator API instead of the embedded QSIMPLEQ entry definitely simplifies logic. Thanks ! > /* > * v9fs_reopen_fid() can yield : a reference on the fid must be held > @@ -534,7 +531,13 @@ static int coroutine_fn v9fs_mark_fids_unreclaim(V9fsPDU *pdu, V9fsPath *path) > * iteration after we could get a reference on the next fid. Start with > * the first one. > */ The comment above should be adapted to the new situation : no need to do anything special with the next fid since we're not getting a pointer to it before calling the "We're done with this fid" put_fid() on the current fid. > - for (fidp->ref++; fidp; fidp = fidp_next) { > + while (g_hash_table_iter_next(&iter, &fid, (gpointer *) &fidp)) { > + /* > + * Ensure the fid survives a potential clunk request during > + * put_fid() below and v9fs_reopen_fid() in the next iteration. With the new logic, this should just be: Ensure the fid survives a potential clunk request during v9fs_reopen_fid(). > + */ > + fidp->ref++; > + > if (fidp->path.size == path->size && > !memcmp(fidp->path.data, path->data, path->size)) { > /* Mark the fid non reclaimable. */ > @@ -548,16 +551,6 @@ static int coroutine_fn v9fs_mark_fids_unreclaim(V9fsPDU *pdu, V9fsPath *path) > } > } > > - fidp_next = QSIMPLEQ_NEXT(fidp, next); > - > - if (fidp_next) { > - /* > - * Ensure the next fid survives a potential clunk request during > - * put_fid() below and v9fs_reopen_fid() in the next iteration. > - */ > - fidp_next->ref++; > - } > - > /* We're done with this fid */ > put_fid(pdu, fidp); > } > @@ -569,19 +562,21 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu) > { > V9fsState *s = pdu->s; > V9fsFidState *fidp; > + gpointer fid; > + GHashTableIter iter; > + > + g_hash_table_iter_init(&iter, s->fids); > > /* Free all fids */ > - while (!QSIMPLEQ_EMPTY(&s->fid_list)) { > - /* Get fid */ > - fidp = QSIMPLEQ_FIRST(&s->fid_list); > + while (g_hash_table_iter_next(&iter, &fid, (gpointer *) &fidp)) { > fidp->ref++; > > /* Clunk fid */ > - QSIMPLEQ_REMOVE(&s->fid_list, fidp, V9fsFidState, next); You could just call g_hash_table_iter_remove(&iter) here (it is safe according to the glib documentation [1]) and... > fidp->clunked = true; > > put_fid(pdu, fidp); > } > + g_hash_table_remove_all(s->fids); ... avoid the extra loop, but no big deal. Rest looks ok. Please re-post and add: Reviewed-by: Greg Kurz Don't forget to put a v3 in the subject and provide the list of changes since v2 below the '---' terminator of the commit message (see [2] for an example). You might want to try out 'git publish' [3], a marvelous tool that helps a lot with the tedious process of posting versionned patch series. Cheers, -- Greg [1] https://developer-old.gnome.org/glib/stable/glib-Hash-Tables.html#g-hash-table-iter-remove [2] https://patchwork.ozlabs.org/project/qemu-devel/patch/20210121181510.1459390-1-groug@kaod.org/ [3] https://github.com/stefanha/git-publish > } > > #define P9_QID_TYPE_DIR 0x80 > @@ -3205,6 +3200,8 @@ static int coroutine_fn v9fs_complete_rename(V9fsPDU *pdu, V9fsFidState *fidp, > V9fsFidState *tfidp; > V9fsState *s = pdu->s; > V9fsFidState *dirfidp = NULL; > + GHashTableIter iter; > + gpointer fid; > > v9fs_path_init(&new_path); > if (newdirfid != -1) { > @@ -3238,11 +3235,13 @@ static int coroutine_fn v9fs_complete_rename(V9fsPDU *pdu, V9fsFidState *fidp, > if (err < 0) { > goto out; > } > + > /* > * Fixup fid's pointing to the old name to > * start pointing to the new name > */ > - QSIMPLEQ_FOREACH(tfidp, &s->fid_list, next) { > + g_hash_table_iter_init(&iter, s->fids); > + while (g_hash_table_iter_next(&iter, &fid, (gpointer *) &tfidp)) { > if (v9fs_path_is_ancestor(&fidp->path, &tfidp->path)) { > /* replace the name */ > v9fs_fix_path(&tfidp->path, &new_path, strlen(fidp->path.data)); > @@ -3320,6 +3319,8 @@ static int coroutine_fn v9fs_fix_fid_paths(V9fsPDU *pdu, V9fsPath *olddir, > V9fsPath oldpath, newpath; > V9fsState *s = pdu->s; > int err; > + GHashTableIter iter; > + gpointer fid; > > v9fs_path_init(&oldpath); > v9fs_path_init(&newpath); > @@ -3336,7 +3337,8 @@ static int coroutine_fn v9fs_fix_fid_paths(V9fsPDU *pdu, V9fsPath *olddir, > * Fixup fid's pointing to the old name to > * start pointing to the new name > */ > - QSIMPLEQ_FOREACH(tfidp, &s->fid_list, next) { > + g_hash_table_iter_init(&iter, s->fids); > + while (g_hash_table_iter_next(&iter, &fid, (gpointer *) &tfidp)) { > if (v9fs_path_is_ancestor(&oldpath, &tfidp->path)) { > /* replace the name */ > v9fs_fix_path(&tfidp->path, &newpath, strlen(oldpath.data)); > @@ -4226,7 +4228,7 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t, > s->ctx.fmode = fse->fmode; > s->ctx.dmode = fse->dmode; > > - QSIMPLEQ_INIT(&s->fid_list); > + s->fids = g_hash_table_new(NULL, NULL); > qemu_co_rwlock_init(&s->rename_lock); > > if (s->ops->init(&s->ctx, errp) < 0) { > @@ -4286,6 +4288,10 @@ void v9fs_device_unrealize_common(V9fsState *s) > if (s->ctx.fst) { > fsdev_throttle_cleanup(s->ctx.fst); > } > + if (s->fids) { > + g_hash_table_destroy(s->fids); > + s->fids = NULL; > + } > g_free(s->tag); > qp_table_destroy(&s->qpd_table); > qp_table_destroy(&s->qpp_table); > diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h > index 994f952600..10fd2076c2 100644 > --- a/hw/9pfs/9p.h > +++ b/hw/9pfs/9p.h > @@ -339,7 +339,7 @@ typedef struct { > struct V9fsState { > QLIST_HEAD(, V9fsPDU) free_list; > QLIST_HEAD(, V9fsPDU) active_list; > - QSIMPLEQ_HEAD(, V9fsFidState) fid_list; > + GHashTable *fids; > FileOperations *ops; > FsContext ctx; > char *tag;